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	Make Podman pod operations that do not involve starting containers (which needs to be done in a specific order) use the same parallel operation code we use to make `podman stop` on large numbers of containers fast. We were previously stopping containers in a pod serially, which could take up to the timeout (default 15 seconds) for each container - stopping 100 containers that do not respond to SIGTERM would take 25 minutes. To do this, refactor the parallel operation code a bit to remove its dependency on libpod (damn circular import restrictions...) and use parallel functions that just re-use the standard container API operations - maximizes code reuse (previously each pod handler had a separate implementation of the container function it performed). This is a bit of a palate cleanser after fighting CI for two days - nice to be able to return to a land of sanity. Signed-off-by: Matthew Heon <matthew.heon@pm.me>
		
			
				
	
	
		
			75 lines
		
	
	
		
			1.8 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
			
		
		
	
	
			75 lines
		
	
	
		
			1.8 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
package parallel
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import (
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	"context"
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	"sync"
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	"github.com/pkg/errors"
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	"github.com/sirupsen/logrus"
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	"golang.org/x/sync/semaphore"
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)
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var (
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	// Maximum number of jobs that will be used.
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	// Set a low, but non-zero, default. We'll be overriding it by default
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	// anyways.
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	numThreads uint = 8
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	// Semaphore to control thread creation and ensure numThreads is
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	// respected.
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	jobControl *semaphore.Weighted
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	// Lock to control changing the semaphore - we don't want to do it
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	// while anyone is using it.
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	jobControlLock sync.RWMutex
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)
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// SetMaxThreads sets the number of threads that will be used for parallel jobs.
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func SetMaxThreads(threads uint) error {
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	if threads == 0 {
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		return errors.New("must give a non-zero number of threads to execute with")
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	}
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	jobControlLock.Lock()
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	defer jobControlLock.Unlock()
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	numThreads = threads
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	jobControl = semaphore.NewWeighted(int64(threads))
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	logrus.Infof("Setting parallel job count to %d", threads)
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	return nil
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}
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// GetMaxThreads returns the current number of threads that will be used for
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// parallel jobs.
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func GetMaxThreads() uint {
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	return numThreads
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}
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// Enqueue adds a single function to the parallel jobs queue. This function will
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// be run when an unused thread is available.
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// Returns a receive-only error channel that will return the error (if any) from
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// the provided function fn when fn has finished executing. The channel will be
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// closed after this.
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func Enqueue(ctx context.Context, fn func() error) <-chan error {
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	retChan := make(chan error)
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	go func() {
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		jobControlLock.RLock()
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		defer jobControlLock.RUnlock()
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		defer close(retChan)
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		if err := jobControl.Acquire(ctx, 1); err != nil {
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			retChan <- errors.Wrapf(err, "error acquiring job control semaphore")
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			return
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		}
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		err := fn()
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		jobControl.Release(1)
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		retChan <- err
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	}()
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	return retChan
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}
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