Patent Publication Number: US-2023153175-A1

Title: Surrogate process creation technique for high process-per-server scenarios

Description:
BACKGROUND 
     The present disclosure relates to launching parallel processes for a parallel application, and more specifically launching parallel processes using a surrogate. 
     Current process for launching parallel processes is to launch the processes in a serial manner. This approach creates significant overhead in the system and impacts the overall performance of the underlying system. As the launch mechanism for launching the parallel processes has many responsibilities the resulting increase in the memory footprint causes even more overhead to be placed on the system during process creation. 
     SUMMARY 
     Embodiments of the present disclosure are directed to a method for launching parallel processes on a server. A request is received from a parallel application to start a number of parallel processes. In response to this request a launcher creates a surrogate. The surrogate inherits communications channels from the launcher. The surrogate then executes activities related to the launch of the parallel processes, and then launches the parallel processes. The parallel processes are launched and the surrogate is terminated. 
     Embodiment of the present disclosure are directed to a system for launching parallel processes on a server configured to process a number of parallel processes. The system includes a parallel application configured to request a number of parallel processes, and a launcher configured to create a surrogate. The launcher is further configured to coordinate with other system services, provide runtime information to peer process, and make resource allocations to processes. The surrogate is configured to launch the number of parallel processes without further involvement of the launcher. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings included in the present application are incorporated into, and form part of, the specification. They illustrate embodiments of the present disclosure and, along with the description, serve to explain the principles of the disclosure. The drawings are only illustrative of certain embodiments and do not limit the disclosure. 
         FIG.  1    is a block diagram illustrating a system for launching a number of unique cooperating processes on a server at the same time according to embodiments. 
         FIG.  2    is a flow diagram illustrating a process for efficiently launching parallel processes using a surrogate while leaving a launcher free to perform other tasks according to embodiments. 
         FIG.  3    is a block diagram illustrating a computing system according to one embodiment. 
         FIG.  4    is a diagrammatic representation of an illustrative cloud computing environment. 
         FIG.  5    illustrates a set of functional abstraction layers provided by cloud computing environment according to one illustrative embodiment. 
     
    
    
     While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. 
     DETAILED DESCRIPTION 
     Aspects of the present disclosure relates to launching parallel processes for a parallel application, and more specifically launching parallel processes using a surrogate. While the present disclosure is not necessarily limited to such applications, various aspects of the disclosure may be appreciated through a discussion of various examples using this context. 
       FIG.  1    is a block diagram illustrating a system for launching a number of unique cooperating processes on a server at the same time. System includes a parallel application  110 , a server  120 , a launcher  130 , a parent process  140 , and a surrogate  150 . 
     Parallel application  110  is an application that divides a large task into a number of smaller processes that execute at or near the same time. Each of these smaller processes are referred to as parallel or child processes  160   160 - 1 ,  160 - 2 ,  160 - 3 , . . .  160 -N (collectively  160 ). The computational task of the parallel application  110  as represented by the parallel processes  160  are executed independently of each other and the results of their completion are then combined to generate a final result. However, in some embodiments the parallel processes can communicate with other parallel processes to share data and/or coordinate their actions. The parallel application  110  can implement bit-level parallelism, instruction level parallelism, task parallelism, or superword level parallelism. 
     The server  120  is a component of the system that processes requests from the parallel application  110 . The server  120  contains a large number of execution units. These execution units are often organized into sockets, cores, and hardware threads. The parallel application  110  using one or more servers can decide to place one process (or thread) per the smallest execution unit to drive the maximum amount of performance from the server for their application. 
     The launcher  130  is a parallel application  110  launch mechanism that is responsible for starting all of the processes in the parallel application  110  at the same time on the set of servers assigned to the application. The launcher  130  directs the creation of the processes, sets up the environment for the processes, registers them with system monitoring services, maps those processes to the execution units, and binds server resources to each process. The launcher  130  further routes standard input and output for each process to a central location. However, other locations can be used. This approach to launching the processes is overhead in the system. The launcher  130  is further configured to minimize this overhead to increase system utilization. The launcher  130  can exist on the server that the processes are launched on or can be located on different server. 
     In Linux, a single process is created by using the fork( )function call that logically duplicates the memory of the parent process  140  into the child process  160 . This operation does not actually copy the memory of the parent process  140  but instead makes a copy of the parent process  140 ′s page table and uses a copy-on-write mechanism to improve the efficiency of fork( ) before a later exec( )call in the child process  160 . The fork( )system call is serialized in the kernel when creating the child process  160  with overhead in relation to the memory footprint of the parent process  140 . The overhead of the copy-on-write mechanism is in relation to the degree to which the parent and child process  160  change memory pages while linked this way. If the copy-on-write mechanism is not in place then the fork overhead can cause considerable limitations on the functionality of the system. 
     The launcher  130  implements an efficient mechanism to start N unique, cooperating processes on a server  120  at the same time. The launcher  130  in addition to creating the processes is tasked with coordinating with other system services, providing runtime information to peer and child processes  160 , and allocating resources on the server  120 . Other additional tasks can also be given to the launcher  130 . Given the number of additional tasks that are placed on the launcher  130 , the launcher  130  has a moderate and often changing memory footprint that causes additional process creation overhead in the fork( )system call. Parallel applications placing a large number of processes-per-server incur high overheads associated with process creation because of these factors. 
     The parent process  140  is a process that is created by the launcher  130 . The launcher  130  is commonly the parent process  140  for the fork( )system call. If the launcher  130  resides on a different server then it will create a delegate launcher parent process  140  on the designed server. The parent process  140  is configured to create communication channels (e.g., pipe file descriptors) for each of the N child processes  160 . The parent process  140  is further configured to establish for each of the child processes  160  any system resources that are required to be established for the initial fork( )call. 
     The surrogate  150  is a component of the system that is configured to perform the process of creating the child processes  160 . The surrogate  150  is created by the parent process  140  when the initial fork is called. The surrogate  150  inherits all of the communications channels for each child process  160  from the parent process  140 , and passes these channels to the child as the child is created by the surrogate  150 . The surrogate  150  also relays commands from the launcher  130  and parent process  140  to each child process  160 . In some embodiments the surrogate  150  monitors each child process  160  during the execution of the child process  160  and notifies the launcher  130  and/or parent process  140  of the completion of the child processes  160 . In some embodiments the surrogate  150  terminates itself once all of the child processes  160  have been launched. In this embodiment, the child processes  160  are left without a parent (orphaned) and then must be reparented to either the launcher  130  or the parent process  140 . Similar to the launcher  130 , the surrogate  150  can be created on the server that the processes are launched on or can be located on different server. The launcher  130  and the surrogate  150  can be on different servers. 
       FIG.  2    is a flow diagram illustrating a process  200  for efficiently launching parallel processes using a surrogate  150  while leaving a launcher  130  free to perform other tasks. 
     The process begins when the launcher  130  receives a request from the parallel application  110  to start a number of processes on a server  120 . This is illustrated at step  210 . The number of processes that are requested can be any number of processes N. In some embodiments, the request is for a specific server. However, the request can be a general request for the application to start on a server or any set of servers. In this embodiment, the launcher  130  can choose a particular server to host the application. The launcher  130  can select the server based on expected performance of the server, the number of processes already executing on the server, or any other metric that is available to the launcher  130 . 
     The launcher  130  implements the surrogate  150  of the present disclosure for all launches of the process requested. However, in some embodiments, the launcher  130  can decide to implement the surrogate  150  on some, but not all of the processes requested. In some embodiments, the launcher  130  can implement the surrogate  150  on a number of processes that exceed a predetermined threshold number of processes for N number of processes requested. That is, for example, the request was for  400  processes and the threshold number of processes is  200 , then the launcher  130  would use the surrogate  150  for  200  instances of the process while launching normally the remaining  200  instances of the process. In some embodiments, the launcher  130  can decide to use multiple surrogate  150  processes each responsible for a portion of the child process launches. 
     The launcher  130  creates a parent process  140  prior to creating the surrogate  150 . This is illustrated at step  220 . The parent process  140  creates a communication channel set (e.g., pipe file descriptors) for each of the N child processes  160  resulting in N communications channels. The parent process  140  also establishes for the child processes  160  any system resources that are required to be established for the first fork( )call. 
     The launcher  130  also creates a communication channel (e.g., a pipe file descriptor) dedicated to launcher-to-surrogate  150  communication. This is illustrated at step  230 . 
     The parent process  140  then creates the surrogate  150 . This is illustrated at step  240 . In some embodiments, the parent process  140  creates the surrogate  150  by calling the primary fork( ) The surrogate  150  calls exec( )on a dedicated surrogate  150  binary for the surrogate  150  activity. The surrogate  150  is configured to minimize the activity necessary to be completed between the fork( )call and surrogate  150  exec( )call. 
     Once the surrogate  150  has been created, the surrogate  150  inherits communications channels from the launcher  130  and parent process  140 . This is illustrated at step  250 . At this step, the surrogate  150  inherits the N communication channel sets for the children and the launcher-to-surrogate  150  communication channel  155  across the fork( )and exec( )calls. 
     The launcher  130  provides additional information to the surrogate  150 . This is illustrated at step  260 . The launcher  130  uses the launcher-to-surrogate  150  communication channel  155  to instruct the surrogate  150  which of the N communication channels go to which child process  160  that will be created by the surrogate  150 . Additionally, the launcher  130  can inform the surrogate  150  of general activities (e.g., environment variables, interactions with system services, etc.) that apply to all processes before the fork( )call and after the exec( )call, and per-process specific activities (e.g., environment variables, binding, synchronization requirements with the launcher  130  parent before the exec( )call) that apply to specific processes. 
     The surrogate  150  performs the general activities designated to be performed before the fork( )call. This is illustrated at step  270 . The surrogate  150  then launches each of the N processes in quick succession. This is illustrated at step  280 . In each child process  160 , after the fork( )call but before the exec( )call the N-1 communication channels not intended for this child process  160  are closed and the one communication channel dedicated to this child is connected directly to the launcher  130 . If the launcher  130  is required to take action per child process  160  after the fork( )call but before the exec( )call the launcher  130  can coordinate that activity through the surrogate  150 . However, in some embodiments the launcher  130  can take the action on its own by using the communication channel with that one child process  160  directly without involving the surrogate  150 . 
     Once the child processes  160  are launched, they are allowed to proceed to execute. This is illustrated at step  290 . In some embodiments, if a synchronized execution is desired, the surrogate  150  then only allows the child processes  160  to execute once all child processes  160  have reached the synchronization point. In some embodiments, the child processes  160  can initiate the exec( )call as soon as they are ready to do so. In this embodiment, the surrogate  150  uses the launcher-to-surrogate  150  communication channel  155  to inform the launcher  130  that the N children have been stared and their per-process identifiers (PID) for tracking. 
     If the operating system allows for re-parenting of the child processes  160  then the surrogate  150  transfers ownership/control of the N children to the launcher  130  at the time of the execute call. After which the surrogate  150  can terminate. However, if the operating system does not allow for re-parenting of the child processes  160  then the surrogate  150  must persist until the last child has exited. The surrogate  150  uses the launcher-to-surrogate  150  communication channel  155  to provide the launcher  130  a protocol based channel to perform per child tracking (e.g., waitpid) and control (e.g., signaling) operations that are not permitted by the operating system for indirectly connected processes. 
     Referring now to  FIG.  3   , shown is a high-level block diagram of an example computer system  301  that may be used in implementing one or more of the methods, tools, and modules, and any related functions, described herein (e.g., using one or more processor circuits or computer processors of the computer), such as the surrogate process for launching parallel processes in accordance with embodiments of the present disclosure. In some embodiments, the major components of the computer system  301  may comprise one or more CPUs  302 , a memory subsystem  304 , a terminal interface  312 , a storage interface  316 , an I/O (Input/Output) device interface  314 , and a network interface  318 , all of which may be communicatively coupled, directly or indirectly, for inter-component communication via a memory bus  303 , an I/O bus  308 , and an I/O bus interface unit  310 . 
     The computer system  301  may contain one or more general-purpose programmable central processing units (CPUs)  302 A,  302 B,  302 C, and  302 D, herein generically referred to as the CPU  302 . In some embodiments, the computer system  301  may contain multiple processors typical of a relatively large system; however, in other embodiments the computer system  301  may alternatively be a single CPU system. Each CPU  302  may execute instructions stored in the memory subsystem  304  and may include one or more levels of on-board cache. 
     System memory  304  may include computer system readable media in the form of volatile memory, such as random access memory (RAM)  322  or cache memory  324 . Computer system  301  may further include other removable/non-removable, volatile/non-volatile computer system storage media. By way of example only, storage system  326  can be provided for reading from and writing to a non-removable, non-volatile magnetic media, such as a “hard drive.” Although not shown, a magnetic disk drive for reading from and writing to a removable, non-volatile magnetic disk (e.g., a “floppy disk”), or an optical disk drive for reading from or writing to a removable, non-volatile optical disc such as a CD-ROM, DVD-ROM or other optical media can be provided. In addition, memory  304  can include flash memory, e.g., a flash memory stick drive or a flash drive. Memory devices can be connected to memory bus  303  by one or more data media interfaces. The memory  304  may include at least one program product having a set (e.g., at least one) of program modules that are configured to carry out the functions of various embodiments. 
     Although the memory bus  303  is shown in  FIG.  3    as a single bus structure providing a direct communication path among the CPUs  302 , the memory subsystem  304 , and the I/O bus interface  310 , the memory bus  303  may, in some embodiments, include multiple different buses or communication paths, which may be arranged in any of various forms, such as point-to-point links in hierarchical, star or web configurations, multiple hierarchical buses, parallel and redundant paths, or any other appropriate type of configuration. Furthermore, while the I/O bus interface  310  and the I/O bus  308  are shown as single respective units, the computer system  301  may, in some embodiments, contain multiple I/O bus interface units  310 , multiple I/O buses  308 , or both. Further, while multiple I/O interface units are shown, which separate the I/O bus  308  from various communications paths running to the various I/O devices, in other embodiments some or all of the I/O devices may be connected directly to one or more system I/O buses. 
     In some embodiments, the computer system  301  may be a multi-user mainframe computer system, a single-user system, or a server computer or similar device that has little or no direct user interface, but receives requests from other computer systems (clients). Further, in some embodiments, the computer system  301  may be implemented as a desktop computer, portable computer, laptop or notebook computer, tablet computer, pocket computer, telephone, smart phone, network switches or routers, or any other appropriate type of electronic device. 
     It is noted that  FIG.  3    is intended to depict the representative major components of an exemplary computer system  301  that implements the surrogate process of the present disclosure. In some embodiments, however, individual components may have greater or lesser complexity than as represented in  FIG.  3   , components other than or in addition to those shown in  FIG.  3    may be present, and the number, type, and configuration of such components may vary. 
     One or more programs/utilities  328 , each having at least one set of program modules  330  may be stored in memory  304 . The programs/utilities  328  may include a hypervisor (also referred to as a virtual machine monitor), one or more operating systems, one or more application programs, other program modules, and program data. Each of the operating systems, one or more application programs, other program modules, and program data or some combination thereof, may include an implementation of a networking environment. Programs  328  and/or program modules  330  generally perform the functions or methodologies of various embodiments. 
     It is to be understood that although this disclosure includes a detailed description on cloud computing, implementation of the teachings recited herein are not limited to a cloud computing environment. Rather, embodiments of the present invention are capable of being implemented in conjunction with any other type of computing environment now known or later developed. 
     Cloud computing is a model of service delivery for enabling convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, network bandwidth, servers, processing, memory, storage, applications, virtual machines, and services) that can be rapidly provisioned and released with minimal management effort or interaction with a provider of the service. This cloud model may include at least five characteristics, at least three service models, and at least four deployment models. 
     Characteristics are as follows: 
     On-demand self-service: a cloud consumer can unilaterally provision computing capabilities, such as server time and network storage, as needed automatically without requiring human interaction with the service&#39;s provider. 
     Broad network access: capabilities are available over a network and accessed through standard mechanisms that promote use by heterogeneous thin or thick client platforms (e.g., mobile phones, laptops, and PDAs). 
     Resource pooling: the provider&#39;s computing resources are pooled to serve multiple consumers using a multi-tenant model, with different physical and virtual resources dynamically assigned and reassigned according to demand. There is a sense of location independence in that the consumer generally has no control or knowledge over the exact location of the provided resources but may be able to specify location at a higher level of abstraction (e.g., country, state, or datacenter). 
     Rapid elasticity: capabilities can be rapidly and elastically provisioned, in some cases automatically, to quickly scale out and rapidly released to quickly scale in. To the consumer, the capabilities available for provisioning often appear to be unlimited and can be purchased in any quantity at any time. 
     Measured service: cloud systems automatically control and optimize resource use by leveraging a metering capability at some level of abstraction appropriate to the type of service (e.g., storage, processing, bandwidth, and active user accounts). Resource usage can be monitored, controlled, and reported, providing transparency for both the provider and consumer of the utilized service. 
     Service Models are as follows: 
     Software as a Service (SaaS): the capability provided to the consumer is to use the provider&#39;s applications running on a cloud infrastructure. The applications are accessible from various client devices through a thin client interface such as a web browser (e.g., web-based e-mail). The consumer does not manage or control the underlying cloud infrastructure including network, servers, operating systems, storage, or even individual application capabilities, with the possible exception of limited user-specific application configuration settings. 
     Platform as a Service (PaaS): the capability provided to the consumer is to deploy onto the cloud infrastructure consumer-created or acquired applications created using programming languages and tools supported by the provider. The consumer does not manage or control the underlying cloud infrastructure including networks, servers, operating systems, or storage, but has control over the deployed applications and possibly application hosting environment configurations. 
     Infrastructure as a Service (IaaS): the capability provided to the consumer is to provision processing, storage, networks, and other fundamental computing resources where the consumer is able to deploy and run arbitrary software, which can include operating systems and applications. The consumer does not manage or control the underlying cloud infrastructure but has control over operating systems, storage, deployed applications, and possibly limited control of select networking components (e.g., host firewalls). 
     Deployment Models are as follows: 
     Private cloud: the cloud infrastructure is operated solely for an organization. It may be managed by the organization or a third party and may exist on-premises or off-premises. 
     Community cloud: the cloud infrastructure is shared by several organizations and supports a specific community that has shared concerns (e.g., mission, security requirements, policy, and compliance considerations). It may be managed by the organizations or a third party and may exist on-premises or off-premises. 
     Public cloud: the cloud infrastructure is made available to the general public or a large industry group and is owned by an organization selling cloud services. 
     Hybrid cloud: the cloud infrastructure is a composition of two or more clouds (private, community, or public) that remain unique entities but are bound together by standardized or proprietary technology that enables data and application portability (e.g., cloud bursting for load-balancing between clouds). 
     A cloud computing environment is service oriented with a focus on statelessness, low coupling, modularity, and semantic interoperability. At the heart of cloud computing is an infrastructure that includes a network of interconnected nodes. 
     The system  100  may be employed in a cloud computing environment.  FIG.  4   , is a diagrammatic representation of an illustrative cloud computing environment  450  according to one embodiment. As shown, cloud computing environment  450  comprises one or more cloud computing nodes  454  with which local computing devices used by cloud consumers, such as, for example, personal digital assistant (PDA) or cellular telephone  454 A, desktop computer  454 B, laptop computer  454 C, and/or automobile computer system  454 N may communicate. Nodes  454  may communicate with one another. They may be grouped (not shown) physically or virtually, in one or more networks, such as Private, Community, Public, or Hybrid clouds as described hereinabove, or a combination thereof. This allows cloud computing environment  450  to offer infrastructure, platforms and/or software as services for which a cloud consumer does not need to maintain resources on a local computing device. It is understood that the types of computing devices  454 A-N shown in  FIG.  4    are intended to be illustrative only and that computing nodes  454  and cloud computing environment  450  may communicate with any type of computerized device over any type of network and/or network addressable connection (e.g., using a web browser). 
     Referring now to  FIG.  5   , a set of functional abstraction layers provided by cloud computing environment  450  ( FIG.  4   ) is shown. It should be understood in advance that the components, layers, and functions shown in  FIG.  5    are intended to be illustrative only and embodiments of the disclosure are not limited thereto. As depicted, the following layers and corresponding functions are provided: 
     Hardware and software layer  560  includes hardware and software components. Examples of hardware components include: mainframes  561 ; RISC (Reduced Instruction Set Computer) architecture based servers  562 ; servers  563 ; blade servers  564 ; storage devices  565 ; and networks and networking components  566 . In some embodiments, software components include network application server software  567  and database software  568 . 
     Virtualization layer  570  provides an abstraction layer from which the following examples of virtual entities may be provided: virtual servers  571 ; virtual storage  572 ; virtual networks  573 , including virtual private networks; virtual applications and operating systems  574 ; and virtual clients  575 . 
     In one example, management layer  580  may provide the functions described below. Resource provisioning  581  provides dynamic procurement of computing resources and other resources that are utilized to perform tasks within the cloud computing environment. Metering and Pricing  582  provide cost tracking as resources are utilized within the cloud computing environment, and billing or invoicing for consumption of these resources. In one example, these resources may comprise application software licenses. Security provides identity verification for cloud consumers and tasks, as well as protection for data and other resources. User portal  583  provides access to the cloud computing environment for consumers and system administrators. Service level management  584  provides cloud computing resource allocation and management such that required service levels are met. Service Level Agreement (SLA) planning and fulfillment  585  provide pre-arrangement for, and procurement of, cloud computing resources for which a future requirement is anticipated in accordance with an SLA. 
     Workloads layer  590  provides examples of functionality for which the cloud computing environment may be utilized. Examples of workloads and functions which may be provided from this layer include: mapping and navigation  591 ; software development and lifecycle management  592 ; layout detection  593 ; data analytics processing  594 ; transaction processing  595 ; and database  596 . 
     The present invention may be a system, a method, and/or a computer program product at any possible technical detail level of integration. The computer program product may include a computer readable storage medium (or media) having computer readable program instructions thereon for causing a processor to carry out aspects of the present invention. 
     The computer readable storage medium can be a tangible device that can retain and store instructions for use by an instruction execution device. The computer readable storage medium may be, for example, but is not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. A non-exhaustive list of more specific examples of the computer readable storage medium includes the following: a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanically encoded device such as punch-cards or raised structures in a groove having instructions recorded thereon, and any suitable combination of the foregoing. A computer readable storage medium, as used herein, is not to be construed as being transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide or other transmission media (e.g., light pulses passing through a fiber-optic cable), or electrical signals transmitted through a wire. 
     Computer readable program instructions described herein can be downloaded to respective computing/processing devices from a computer readable storage medium or to an external computer or external storage device via a network, for example, the Internet, a local area network, a wide area network and/or a wireless network. The network may comprise copper transmission cables, optical transmission fibers, wireless transmission, routers, firewalls, switches, gateway computers and/or edge servers. A network adapter card or network interface in each computing/processing device receives computer readable program instructions from the network and forwards the computer readable program instructions for storage in a computer readable storage medium within the respective computing/processing device. 
     Computer readable program instructions for carrying out operations of the present invention may be assembler instructions, instruction-set-architecture (ISA) instructions, machine instructions, machine dependent instructions, microcode, firmware instructions, state-setting data, configuration data for integrated circuitry, or either source code or object code written in any combination of one or more programming languages, including an object oriented programming language such as Smalltalk, C++, or the like, and procedural programming languages, such as the “C” programming language or similar programming languages. The computer readable program instructions may execute entirely on the user&#39;s computer, partly on the user&#39;s computer, as a stand-alone software package, partly on the user&#39;s computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user&#39;s computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider). In some embodiments, electronic circuitry including, for example, programmable logic circuitry, field-programmable gate arrays (FPGA), or programmable logic arrays (PLA) may execute the computer readable program instructions by utilizing state information of the computer readable program instructions to personalize the electronic circuitry, in order to perform aspects of the present invention. 
     Aspects of the present invention are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer readable program instructions. 
     These computer readable program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. These computer readable program instructions may also be stored in a computer readable storage medium that can direct a computer, a programmable data processing apparatus, and/or other devices to function in a particular manner, such that the computer readable storage medium having instructions stored therein comprises an article of manufacture including instructions which implement aspects of the function/act specified in the flowchart and/or block diagram block or blocks. 
     The computer readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other device to produce a computer implemented process, such that the instructions which execute on the computer, other programmable apparatus, or other device implement the functions/acts specified in the flowchart and/or block diagram block or blocks. 
     The flowchart and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of instructions, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the blocks may occur out of the order noted in the Figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts or carry out combinations of special purpose hardware and computer instructions. 
     The descriptions of the various embodiments of the present disclosure have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein was chosen to explain the principles of the embodiments, the practical application or technical improvement over technologies found in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.