Abstract:
Necessary resources are assigned to programs based on a program reservation information management table in which each of the programs is associated with a necessary resource quantity for execution of the program and execution scheduled time period as program reservation information. When the program reservation information is entered through a terminal, a free resource quantity management table in which available resource quantities are associated with respective time periods is referred to, and it is determined whether the available resource quantity for the execution scheduled time period is at or above the necessary resource quantity. When having determined that the available resource quantity is at or above the necessary resource quantity, the necessary resource quantity is subtracted from the available resource quantity, and the subtracting result is written as a new value of the available resource quantity into the free resource quantity management table, and the program reservation information is written into the program reservation information management table.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application claims priority upon Japanese Patent Application No. 2004-165576 filed on Jun. 3, 2004, which is herein incorporated by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a method, apparatus, and program of making reservations for execution of programs, and a program execution system.  
         [0004]     2. Description of the Related Art  
         [0005]     Among computing systems having grid computing technology applied thereto are systems comprising an apparatus of making reservations for execution of jobs, which apparatus can access a so-called resource pool containing a plurality of computers (resources) that execute jobs (programs) of this computation. This apparatus of making reservations for execution of jobs comprises a job reservation information management table, and has a function to assign computers of the resource pool to jobs based on this table. The job reservation information management table contains table data wherein each job is associated with the number of computers required for execution of a job and an execution scheduled time as job reservation information. Such technology is disclosed in, for example, Japanese Patent Application Laid-open Publication No. 2002-318791.  
         [0006]     As illustrated in, for example, a time diagram of FIG.  12 A, the reservation status of computers (machines  1  to  4 ) is considered where machines  1  and  2  are reserved for the period of 12:00 to 14:00 for job A and machine  2  is reserved for the period of 16:00 to 18:00 for job B. In this case, the job reservation information management table is configured such that machines  1  and  2  are to be assigned to job A for the period of 12:00 to 14:00 and machine  2  is to be assigned to job B for the period of 16:00 to 18:00.  
         [0007]     For this reservation status it is possible to execute, for example, job C that uses two machines for four hours, from 13:00. By making this reservation for job C, the reservation status is updated to a reservation status illustrated in a time diagram of  FIG. 12B . Note that it is assumed that all machines  1  to  4  are equal in computation capability.  
         [0008]     In the above computing system, reservations for jobs are made by specifically assigning computers to the jobs in the job reservation information management table. For example, in the case where job B is assigned to machine  3  but not machine  1  or  2  as illustrated in a time diagram of  FIG. 12C , the problem that reservations for job C cannot be made occurs due to the premise that the same computer is consecutively used. This means that the computers are not being efficiently used.  
       SUMMARY OF THE INVENTION  
       [0009]     The present invention was made in view of the above problem, and an object of the present invention is to enable the execution of jobs using resources efficiently.  
         [0010]     The invention to solve the above problem is a program execution reservation method of assigning necessary resources to programs based on a program reservation information management table in which each of the programs is associated with a necessary resource quantity for execution of the program and execution scheduled time period as program reservation information, the method comprising, when the program reservation information is entered through a terminal, referring to a free resource quantity management table in which available resource quantities are associated with respective time periods, and acquiring the available resource quantity for the execution scheduled time period of the program reservation information, and determining whether the available resource quantity acquired is at or above the necessary resource quantity of the program reservation information; and, when having determined that the available resource quantity acquired is at or above the necessary resource quantity of the program reservation information, subtracting the necessary resource quantity from the available resource quantity, and writing the subtracting result as a new value of the available resource quantity into the free resource quantity management table, and writing the program reservation information into the program reservation information management table to update it.  
         [0011]     In this program execution reservation method, preferably the program reservation information further includes information about an operating system and software necessary for execution of the program, and the method preferably further comprises referring to a preparation period management table in which each combination of an operating system and software is associated with a preparation period necessary for installing them in one of the resources, and acquiring the preparation period for the execution of the program for the program reservation information, and setting a new start time to earlier by the preparation period than the start time of the execution scheduled time period.  
         [0012]     The program execution reservation method may further comprise, at the start time of the execution scheduled time period, referring to a resource use status management table in which each resource is associated with information about whether or not it is being used, and arbitrarily assigning the program a same number of any resources as the corresponding necessary resource quantity in the updated program reservation information management table from among available ones at the start time of the resources.  
         [0013]     Alternatively, the program execution reservation method may further comprise, at the start time of the execution scheduled time period, referring to a resource use status management table in which each resource is associated with information about whether or not it is being used, and restrictively assigning the program a same number of particular resources as the corresponding necessary resource quantity in the updated program reservation information management table from among available ones at the start time of the resources.  
         [0014]     In the foregoing program execution reservation method, the resource quantity may be the number of computers as resources.  
         [0015]     The foregoing method may be a program execution reservation method wherein a plurality of the resources are separated into a plurality of data centers to which the resources belong and resources of each of the data centers are separated into for internal users and for external users, wherein corresponding to the separation, the program reservation information management table and the free resource quantity management table are each separated into for internal users and for external users, wherein the resource use status management table has each resource associated with information indicating one of the data centers and information indicating for internal users or for external users in addition to the information about whether or not it is being used, and wherein the particular resources are selected from among the resources for external users listed in the resource use status management table such that the particular resources are resources belonging to a given one of the data centers only if possible.  
         [0016]     In the foregoing program execution reservation method, in each of the data centers, the ratio of the number of the resources for internal users to the number of the resources for external users may be variable with time.  
         [0017]     Furthermore, the invention to solve the above problem is a program execution reservation apparatus which has a program reservation information management table in which each of programs is associated with a necessary resource quantity for execution of the program and execution scheduled time period as program reservation information, and which assigns necessary resources to the programs based on the program reservation information management table, the apparatus comprising a free resource quantity management table in which available resource quantities are associated with respective time periods; a reservation acceptance/denial determining section that, when the program reservation information is entered through a terminal, referring to the free resource quantity management table, acquires the available resource quantity for the execution scheduled time period of the program reservation information, and determines whether the available resource quantity acquired is at or above the necessary resource quantity of the program reservation information; and a table updating section that, when having determined that the available resource quantity acquired is at or above the necessary resource quantity of the program reservation information, subtracts the necessary resource quantity from the available resource quantity, and writes the subtracting result as a new value of the available resource quantity into the free resource quantity management table, and writes the program reservation information into the program reservation information management table.  
         [0018]     Moreover, the invention to solve the above problem is a program execution reservation program for causing a program execution reservation apparatus having a program reservation information management table in which each of programs is associated with a necessary resource quantity for execution of the program and execution scheduled time period as program reservation information to perform a program execution reservation method of assigning necessary resources to the programs based on the program reservation information management table, the program comprising, when the program reservation information is entered through a terminal, referring to a free resource quantity management table in which available resource quantities are associated with respective time periods, and acquiring the available resource quantity for the execution scheduled time period of the program reservation information, and determining whether the available resource quantity acquired is at or above the necessary resource quantity of the program reservation information; and when having determined that the available resource quantity acquired is at or above the necessary resource quantity of the program reservation information, subtracting the necessary resource quantity from the available resource quantity, and writing the subtracting result as a new value of the available resource quantity into the free resource quantity management table, and writing the program reservation information into the program reservation information management table to update it.  
         [0019]     Yet further, the invention to solve the above problem is a program execution system which has a resource pool containing resources to execute programs; a program execution reservation apparatus having a program reservation information management table in which each of programs is associated with a necessary resource quantity for execution of the program and execution scheduled time period as program reservation information, and a resource assigning section that assigns necessary resources to the programs based on the program reservation information management table; and a terminal to enter the program reservation information therethrough, wherein the program execution reservation apparatus further comprising a free resource quantity management table in which available resource quantities are associated with respective time periods; a resource use status management table in which each resource is associated with information about whether or not it is being used; a reservation acceptance/denial determining section that, when the program reservation information is entered through the terminal, referring to the free resource quantity management table, acquires the available resource quantity for the execution scheduled time period of the program reservation information, and determines whether the available resource quantity acquired is at or above the necessary resource quantity of the program reservation information; and a table updating section that, when having determined that the available resource quantity acquired is at or above the necessary resource quantity of the program reservation information, subtracts the necessary resource quantity from the available resource quantity, and writes the subtracting result as a new value of the available resource quantity into the free resource quantity management table, and writes the program reservation information into the program reservation information management table, and wherein the resource assigning section of the program execution reservation apparatus, at the start time of the execution scheduled time period, referring to the resource use status management table, assigns the program a same number of resources as the corresponding necessary resource quantity in the updated program reservation information management table from among available ones at the start time of the resources.  
         [0020]     By the above means, jobs (programs) can be executed using resources efficiently.  
         [0021]     Features and objects of the present invention other than the above will become clear by reading the description of the present specification with reference to the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]     For more complete understanding of the present invention and the advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings wherein:  
         [0023]      FIG. 1  is a block diagram showing an example of the configuration of a job execution system of a first embodiment;  
         [0024]      FIG. 2A  is a chart showing an example of a job reservation information management table of the first embodiment;  
         [0025]      FIG. 2B  is a chart showing an example of a free resource quantity management table of the first embodiment;  
         [0026]      FIG. 2C  is a chart showing an example of a preparation period management table of the first embodiment;  
         [0027]      FIG. 2D  is a chart showing an example of a resource use status management table of the first embodiment;  
         [0028]      FIG. 3  is a flow chart showing an example of a processing procedure of a job execution reservation method of the first embodiment;  
         [0029]      FIG. 4  is a chart showing another example of the free resource quantity management table of the first embodiment;  
         [0030]      FIG. 5  is a chart showing another example of the job reservation information management table of the first embodiment;  
         [0031]      FIG. 6  is a flow chart showing an example of a processing procedure of a job execution method of the first embodiment;  
         [0032]      FIG. 7A  is a time diagram showing an example of resource assignment of the first embodiment;  
         [0033]      FIG. 7B  is a time diagram showing an example of resource assignment of the first embodiment;  
         [0034]      FIG. 7C  is a time diagram showing an example of resource assignment of the first embodiment;  
         [0035]      FIG. 8  is a block diagram showing an example of the configuration of a job execution system of a second embodiment;  
         [0036]      FIG. 9A  is a pattern diagram showing an example of resource assignment at job execution reservation in the second embodiment;  
         [0037]      FIG. 9B  is a pattern diagram showing an example of resource assignment at job execution start in the second embodiment;  
         [0038]      FIG. 10  is a chart showing an example of a resource use status management table at job execution reservation of the second embodiment;  
         [0039]      FIG. 11  is a chart showing an example of the resource use status management table at job execution start of the second embodiment;  
         [0040]      FIG. 12A  is a time diagram showing an example of resource assignment;  
         [0041]      FIG. 12B  is a time diagram showing an example of resource assignment; and  
         [0042]      FIG. 12C  is a time diagram showing an example of resource assignment. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0043]     At least the following matters will be made clear by the explanation in the present specification and the description of the accompanying drawings.  
       First Embodiment  
       [0044]     &lt;&lt;Job Execution Reservation Apparatus&gt;&gt; 
         [0045]     As illustrated in a block diagram of  FIG. 1 , a grid computing system (program execution system)  10  of the present embodiment comprises essentially a resource pool  30  containing a plurality of computers (resources)  31   a ,  31   b ,  31   c ,  31   d  for executing grid computation jobs, and a resource reservation management apparatus (program execution reservation apparatus)  50 . Note that although being four in  FIG. 1 , the number of the computers  31  is not limited to this, but can be any number as long as being two or greater. Furthermore, it is assumed that all computers  31  of the present embodiment are the same in capabilities.  
         [0046]     The resource reservation/management apparatus  50  comprises operating systems (OS) that are to be installed in the computers  31  when jobs are executed, premise software, applications (AP), an AP repository  70  storing setting information and the like, and an operator terminal (or terminal)  90  for an operator to enter job reservation information and the like therethrough. This resource reservation/management apparatus  50  is an information processing apparatus that makes reservations for the execution of jobs based on the job reservation information and has a function to cause computers  31  to execute jobs.  
         [0047]     Note that the resource reservation/management apparatus  50  of the present embodiment is not limited to a separate information processing apparatus, but may be embodied as software installed in one of computers  31  that causes the computer to operate as the resource reservation/management apparatus  50 .  
         [0048]     The resource reservation/management apparatus  50  further comprises a reservation information management table (program reservation information management table)  110 , a number-of-unoccupied-machines management table (free resource quantity management table)  130 , a system preparation time management table (preparation period management table)  150 , and an execution machine management table (resource use status management table)  170 . In this embodiment, a description will be made taking jobs as an example, but the same applies to programs, objects, processes, and threads.  
         [0049]     As illustrated in a table of  FIG. 2A , the reservation information management table  110  is configured such that, for each operator information piece, the number of to-be-reserved computers  31  (resource quantity) and a job execution scheduled date and time (execution scheduled time period), an OS and premise software necessary for the job, an application, setting information, and the like as job reservation information, which are associated with each other. In  FIG. 2A , for example, an operator X has made a reservation of two computers  31  for the period of 12:00 to 14:00 on January 10. Furthermore, the job for this reservation is to be executed using premise software, “J2EE1.4” and “ftp”, on an OS, “Linux (Trademark)”. Note that although in the present embodiment the reservation information management table  110  is configured on a per operator information piece basis, one configured on a per operator-requested-job basis or on a per application-for-the-job basis would be equivalent thereto. The point is that a resource quantity and execution scheduled time period need only be associated with each information piece identifying a job in the present embodiment.  
         [0050]     As illustrated in a table of  FIG. 2B , the number-of-unoccupied-machines management table  130  is configured so that the number of computers  31  available (resource quantity) is associated with each date and time (term). In  FIG. 2B , for example, the number of unoccupied computers  31  is two for the period of 12:00 to 13:00 on January 10 and two for the period of 13:00 to 14:00 on January 10. Here, considering the number of all computers  31  in the resource pool  30  of the present embodiment being four, it matches the number of unoccupied computers  31  being two that in the reservation information management table  110 , operator X has made reservations of two computers  31  each for both the period of 12:00 to 13:00 and the period of 13:00 to 14:00. That is, data of the number-of-unoccupied-machines management table  130  ( FIG. 2B ) matches data of the reservation information management table  110  ( FIG. 2A ).  
         [0051]     As illustrated in a table of  FIG. 2C , the system preparation time management table  150  is configured so that each combination of an OS and premise software of the above ones is associated with system preparation time (a preparation period) to install the OS and software in a computer  31 . In  FIG. 2C , time required for installing an OS, “Linux (Trademark)”, and premise software, “J2EE1.4” and “ftp”, in a computer  31  is 0.2 hours (12 minutes). And, time required for installing an OS, “Windows (Trademark)”, and premise software, “VisualBasic (Trademark)” and “Excel (Trademark)”, in a computer  31  is 0.4 hours (24 minutes).  
         [0052]     As illustrated in a table of  FIG. 2D , the execution machine management table  170  is configured so that each computer  31   a ,  31   b ,  31   c ,  31   d  is associated with whether or not it is being used at a current time (for example, at 12:48). In  FIG. 2D , for example, two computers  31   a ,  31   b  are used for operator X at 12:48, and two computers  31   c ,  31   d  are not used (free) at 12:48. The operations of the computers  31  are based on the job reservation information. Hence, the two indicated as being used in  FIG. 2D  correspond to two computers  31  reserved by operator X for the period of 12:00 to 14:00 on January 10 in the reservation information management table  110  ( FIG. 2A ), and the two indicated as being not used in  FIG. 2D  correspond to two unoccupied computers  31  for the period of 12:00 to 13:00 on January 10 in the number-of-unoccupied-machines management table  130  ( FIG. 2B ).  
         [0053]     Furthermore, as illustrated in the block diagram of  FIG. 1 , the resource reservation/management apparatus  50  of the present embodiment comprises a resource determining module (resource assigning section)  190  described later which assigns computers  31  to a job at an actual execution start date and time for the job.  
         [0000]     &lt;&lt;&lt;Job Execution Reservation and Job Execution&gt;&gt;&gt; 
         [0054]     As illustrated in a flow chart of  FIG. 3 , first, operator X enters the designations of an application for job C to be executed, an OS, and premise software, and the number of computers  31  to be reserved and a date and time to be reserved for, which are job reservation information, into the resource reservation/management apparatus  50  of the grid computing system  10  through the operator terminal  90  (S 200 ). In the present embodiment, it is assumed that the OS is “Linux (Trademark)”, the premise software is “J2EE1.4” and “ftp”, the number of computers  31  to be reserved is two, and the date and time to be reserved for is the period of 13:00 to 17:00 on January 10. Note that in the present embodiment, reservations are already made by the same operator X for job A and job B, but computers  31  are not yet assigned to jobs as described later.  
         [0055]     Referring to the number-of-unoccupied-machines management table  130  ( FIG. 2B ), the resource reservation/management apparatus  50  acquires the number of computers  31  available at the reservation date and time specified in the job reservation information and determines whether or not the number is at or above the number of ones to be reserved specified in the job reservation information (S 201 ).  
         [0056]     According to  FIG. 2B , the number of computers available for the period of 13:00 to 14:00 on January 10 is two, the number of computers available for the period of 14:00 to 15:00 is four, the number of computers available for the period of 15:00 to 16:00 is four, and the number of computers available for the period of 16:00 to 17:00 is three. Thus, the number of computers  31  available for all the period of 13:00 to 17:00 is two, which is equal to the number of computers  31  to be reserved (S 201 : YES).  
         [0057]     If the number of computers available is less than the number of computers to be reserved (S 201 : NO), the resource reservation/management apparatus  50  displays on an appropriate display to the effect that the reservation failed (S 202 ) and finishes processing.  
         [0058]     Next, the resource reservation/management apparatus  50  subtracts two, the number of computers to be reserved, from two, the number of computers available for the period of 13:00 to 14:00, in data for January 10 in the number-of-unoccupied-machines management table  130  ( FIG. 2B ) to produce zero (subtracting result), subtracts two, the number of computers to be reserved, from four, the number of computers available for the period of 14:00 to 15:00, to produce two (subtracting result), subtracts two, the number of computers to be reserved, from four, the number of computers available for the period of 15:00 to 16:00, to produce two (subtracting result), and subtracts two, the number of computers to be reserved, from three, the number of computers available for the period of 16:00 to 17:00, to produce one (subtracting result). By writing the subtracting results as new numbers of computers available, the number-of-unoccupied-machines management table  130  is updated (see  FIG. 4 ). By writing the above job reservation information into the reservation information management table  110  ( FIG. 2A ), the resource reservation/management apparatus  50  updates it (see  FIG. 5 ; S 203 ).  
         [0059]     Next, referring to the system preparation time management table  150  ( FIG. 2C ), the resource reservation/management apparatus  50  acquires system preparation time, 0.2 hours (=12 minutes), associated with the combination (pattern  1 ) of the OS and premise software of the job reservation information. Furthermore, the resource reservation/management apparatus  50  sets the actual execution start date and time for job C to 12:48 on January 10 that is twelve minutes before 13:00 on January 10 and sets an appropriate timer to call up the resource determining module  190  at that date and time (S 204 ).  
         [0060]     Finally, the resource reservation/management apparatus  50  displays on an appropriate display to the effect that the reservation has been made (S 205 ) and finishes processing.  
         [0061]     As illustrated in a flow chart of  FIG. 6 , referring to the execution machine management table  170 , the resource reservation/management apparatus  50  selects any two computers from unoccupied computers  31   c ,  31   d  based on the job reservation information by use of the operation of the resource determining module  190  called up at 12:48 on January 10 as mentioned above, and assigns them to job C (S 300 ). Note that in the present embodiment, there are two unoccupied computers  31   c ,  31   d  and thus, any two computers selected are computers  31   c ,  31   d.    
         [0062]     Next, according to the job reservation information, the resource reservation/management apparatus  50  reads out the OS and premise software necessary for job C from the AP repository  70  and installs them in computers  31   c ,  31   d  (S 301 ).  
         [0063]     Next, according to the job reservation information, the resource reservation/management apparatus  50  reads out the application necessary for job C from the AP repository  70 , installs it in computers  31   c ,  31   d , and sets its operation environment according to the setting information (S 302 ).  
         [0064]     Finally, the resource reservation/management apparatus  50  starts the application at 13:00 (S 303 ).  
         [0065]     Note that the above step S 201  constitutes a determining step of the present embodiment, step S 203  constitutes an updating step of the present embodiment, step S 204  constitutes a step of setting a start time of the present embodiment, and step S 300  constitutes an arbitrarily assigning step of the present embodiment. Moreover, an appropriate CPU provided in the resource reservation/management apparatus  50  and an appropriate program (program execution reservation program) to cause the CPU to perform the process of S 201  constitutes a reservation acceptance/denial determining section of the present embodiment. Furthermore, the appropriate CPU provided in the resource reservation/management apparatus  50  and the appropriate program (program execution reservation program) to cause the CPU to perform the process of S 203  constitutes a table updating section of the present embodiment.  
         [0000]     &lt;&lt;&lt;Resource Assignment&gt;&gt;&gt; 
         [0066]     By the resource reservation/management apparatus  50  of the present embodiment, the reservation information management table  110  of, for example,  FIG. 5  is created through the determination of step S 201  so as to secure consistency with the number-of-unoccupied-machines management table  130  of  FIG. 4 . According to the reservation information management table  110 , job A is to be executed using two computers  31  during the period of 12:00 to 14:00 on January 10; job B is to be executed using one computer  31  during the period of 16:00 to 18:00 on the same day; and job C is to be executed using two computers  31  during the period of 13:00 to 17:00 on the same day.  
         [0067]     Furthermore, by the resource reservation/management apparatus  50  of the present embodiment, in step S 300 , each job is assigned computers  31  at the actual execution start date and time for the job.  
         [0068]     As illustrated in a time diagram of  FIG. 7A , when job A is assigned two computers  31  at 12:00 (actually 11:48) on January 10 based on the number-of-unoccupied-machines management table  130  ( FIG. 5 ), job B and job C are not yet assigned a computer  31 . Hence, any two of the four computers  31  can be assigned to job A. In  FIG. 7A , these two computers are computers  31   a ,  31   b.    
         [0069]     As illustrated in a time diagram of  FIG. 7B , when job C is assigned two computers  31  at 13:00 (actually 12:48) on January 10 based on the number-of-unoccupied-machines management table  130  ( FIG. 5 ), two assignable computers are computers  31   c  and  31   d.    
         [0070]     As illustrated in a time diagram of  FIG. 7C , when job B is assigned one computer  31  at 16:00 (actually 15:36) on January 10 based on the number-of-unoccupied-machines management table  130  ( FIG. 5 ), either of computers  31   a ,  31   b  released from job A can be assigned to job B. In  FIG. 7C , this computer is computer  31   b.    
         [0071]     As described above, the reservation information management table  110  ( FIG. 5 ) is created so as to secure consistency with the number-of-unoccupied-machines management table  130  ( FIG. 4 ), and each job is assigned computers  31  at the actual execution start date and time for the job. By this means, the jobs are executed using the computers  31  efficiently.  
         [0072]     Moreover, by the resource reservation/management apparatus  50  of the present embodiment, execution preparation for each job is started at the actual execution start date and time for the job. Hence, no job finishes later than its scheduled end time. Thus, the jobs are executed using the computers  31  efficiently as scheduled.  
       Second Embodiment  
       [0073]     As illustrated in a block diagram of  FIG. 8 , in the present embodiment, the resource pool  30  of the above embodiment is separated into a plurality of data centers  33 , each of which comprises computers  35  for internal users and for external users.  
         [0074]     The resource reservation/management apparatus  50  assigns jobs for internal users of each data center  33  computers  35  for internal users of the data center  33  according to the above job execution reservation and execution method. In this case, the reservation information management table  110  and the number-of-unoccupied-machines management table  130  are created for the internal users of each data center  33  individually. By this means, the jobs for internal users of each data center  33  can be executed using the computers  35  for internal users of the data center  33  efficiently. That is, the same effect as produced in the above embodiment is produced in the present embodiment as well.  
         [0075]     On the other hand, jobs for external users are assigned computers from among all computers  35  for external users regardless of which data center  33  they belong to. In this case, the reservation information management table  110  and the number-of-unoccupied-machines management table  130  are created for external users separately from those for internal users mentioned above.  
         [0076]     As illustrated in pattern diagrams of  FIGS. 9A and 9B , a job execution reservation method will be described wherein ones of the computers  35  ( 3501  to  3524 ) of data centers A 33   a  and B 33   b  are assigned to a job for an external user.  
         [0077]     It is assumed that when a reservation is made for a job for an external user, as shown in, e.g.,  FIG. 9A , seven for-internal-users computers  3501  to  3507  and five for-external-users computers  3508  to  3512  belong to data centers A 33   a , and five for-internal-users computers  3513  to  3517  and seven for-external-users computers  3518  to  3524  belong to data centers B 33   b . Here, as in the above embodiment, for the job for the external user, ten computers  35  are reserved for a given execution scheduled time.  
         [0078]     As illustrated in a table of  FIG. 10 , when making an execution reservation, the execution machine management table  170  is configured so that the computers  3501  to  3524  are further associated with “A”/“B”, information indicating which data center  33   a ,  33   b  it belongs to, and “internal”/“external”, information for distinguishing users as well as the information about whether or not it is being used when making an execution reservation.  
         [0079]     Here, suppose that, as illustrated in a table of  FIG. 11 , when starting the execution of the job for the external user, five of for-internal-users computers  3501  to  3507  of data center A 33   a  become free and released to be available for external users. That is, in data center A 33   a , the ratio of the number of for-internal-users computers  35  to the number of for-internal-users computers  35  was 7:5 when making an execution reservation, and has changed to 2:10 when starting the execution of the job.  
         [0080]     Specifically, when starting the execution of the job for the external user, as shown in  FIG. 9B , two for-internal-users computers  3501  and  3502  and ten for-external-users computers  3503  to  3512  belong to data center A 33   a , and five for-internal-users computers  3513  to  3517  and seven for-external-users computers  3518  to  3524  belong to data center B 33   b . In this way, in each data center  33 , the number-of-computers ratio is variable with date and time.  
         [0081]     If computers  35  must be specifically assigned to the job when making an execution reservation for the job for the external user, there would be no other choice but to choose ten computers  3508  to  3512  and  3520  to  3524  from both data centers A 33   a , B 33   b  as illustrated in  FIG. 9A .  
         [0082]     On the other hand, the resource reservation/management apparatus  50  of the present embodiment specifically assigns computers  35  when starting the execution of the job for the external user. Hence, if the reservation status has changed from  FIG. 9A  to  FIG. 9B , ten computers can be selected from for-external-users computers  3503  to  3512  and  3518  to  3524 . Thus, the ten computers can be selected from only data center A 33   a . Only if possible, by selecting the ten computers from computers  3503  to  3512  belonging to one data center A 33   a  as above, the job can be executed efficiently without using the broad network. By this means, the overall utilization rate of data centers  33  can be improved.  
         [0083]     Moreover, the effect is produced that when starting the execution of a job, most appropriate computers  35  can be used in terms of network conditions between computers  3501  to  3524 , cost, and the like.  
         [0084]     Note that the above selecting and assigning of ten computers from computers  3503  to  3512  belonging to one data center A 33   a  only if possible constitutes a restrictively assigning step of the present embodiment.  
         [0085]     The above embodiments of the invention are provided to facilitate the understanding of the present invention and not intended to limit the present invention. It should be understood that various changes and alterations can be made therein without departing from the spirit and scope of the present invention and the present invention includes such equivalents.  
         [0086]     Although, in the above embodiments, resources for executing jobs are computers  31 ,  35 , the present invention is not limited to this, but the resource may be embodied as anything such as CPU or memory associated with the execution of a job and to be assigned to the job.