func (p *process) Start(ctx context.Context) error {
	r, err := p.task.client.TaskService().Start(ctx, &tasks.StartRequest{
		ContainerID: p.task.id,
		ExecID:      p.id,
	})
	if err != nil {
		p.io.Cancel()
		p.io.Wait()
		p.io.Close()
		return errdefs.FromGRPC(err)
	}
	p.pid = r.Pid
	return nil
}
Start starts the exec process
package containerd
import (
	"context"
	"strings"
	"syscall"
	"time"
	"github.com/containerd/containerd/api/services/tasks/v1"
	"github.com/containerd/containerd/cio"
	"github.com/containerd/containerd/errdefs"
	"github.com/pkg/errors"
)
type Process interface {
	Pid() uint32
	Start(context.Context) error
	Delete(context.Context, ...ProcessDeleteOpts) (*ExitStatus, error)
	Kill(context.Context, syscall.Signal, ...KillOpts) error
	Wait(context.Context) (<-chan ExitStatus, error)
	CloseIO(context.Context, ...IOCloserOpts) error
	Resize(ctx context.Context, w, h uint32) error
	IO() cio.IO
	Status(context.Context) (Status, error)
}
type ExitStatus struct {
	code     uint32
	exitedAt time.Time
	err      error
}
func (s ExitStatus) Result() (uint32, time.Time, error) {
	return s.code, s.exitedAt, s.err
}
func (s ExitStatus) ExitCode() uint32 {
	return s.code
}
func (s ExitStatus) ExitTime() time.Time {
	return s.exitedAt
}
func (s ExitStatus) Error() error {
	return s.err
}
type process struct {
	id   string
	task *task
	pid  uint32
	io   cio.IO
}
func (p *process) ID() string {
	return p.id
}
func (p *process) Pid() uint32 {
	return p.pid
}