Regulate filesystem driver to max of 100 calls
It's easily possible for a flood of requests to trigger thousands of concurrent file accesses on the storage driver. Each file I/O call creates a new OS thread that is not reaped by the Golang runtime. By limiting it to only 100 at a time we can effectively bound the number of OS threads in use by the storage driver. Docker-DCO-1.1-Signed-off-by: Josh Hawn <josh.hawn@docker.com> (github: jlhawn) Signed-off-by: Tony Holdstock-Brown <tony@docker.com>
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2 changed files with 153 additions and 3 deletions
150
registry/storage/driver/base/regulator.go
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150
registry/storage/driver/base/regulator.go
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package base
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import (
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"io"
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"sync"
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"github.com/docker/distribution/context"
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storagedriver "github.com/docker/distribution/registry/storage/driver"
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)
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type regulator struct {
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storagedriver.StorageDriver
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sync.Cond
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available uint
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}
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// NewRegulator wraps the given driver and is used to regulate concurrent calls
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// to the given storage driver to a maximum of the given limit. This is useful
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// for storage drivers that would otherwise create an unbounded number of OS
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// threads if allowed to be called unregulated.
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func NewRegulator(driver storagedriver.StorageDriver, limit uint) storagedriver.StorageDriver {
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return ®ulator{
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StorageDriver: driver,
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Cond: sync.Cond{
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L: &sync.Mutex{},
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},
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available: limit,
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}
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}
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func (r *regulator) condition() bool {
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return r.available > 0
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}
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func (r *regulator) enter() {
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r.L.Lock()
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defer r.L.Unlock()
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for !r.condition() {
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r.Wait()
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}
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r.available--
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}
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func (r *regulator) exit() {
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r.L.Lock()
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defer r.Signal()
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defer r.L.Unlock()
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r.available++
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}
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// Name returns the human-readable "name" of the driver, useful in error
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// messages and logging. By convention, this will just be the registration
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// name, but drivers may provide other information here.
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func (r *regulator) Name() string {
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r.enter()
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defer r.exit()
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return r.StorageDriver.Name()
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}
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// GetContent retrieves the content stored at "path" as a []byte.
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// This should primarily be used for small objects.
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func (r *regulator) GetContent(ctx context.Context, path string) ([]byte, error) {
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r.enter()
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defer r.exit()
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return r.StorageDriver.GetContent(ctx, path)
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}
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// PutContent stores the []byte content at a location designated by "path".
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// This should primarily be used for small objects.
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func (r *regulator) PutContent(ctx context.Context, path string, content []byte) error {
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r.enter()
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defer r.exit()
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return r.StorageDriver.PutContent(ctx, path, content)
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}
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// ReadStream retrieves an io.ReadCloser for the content stored at "path"
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// with a given byte offset.
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// May be used to resume reading a stream by providing a nonzero offset.
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func (r *regulator) ReadStream(ctx context.Context, path string, offset int64) (io.ReadCloser, error) {
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r.enter()
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defer r.exit()
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return r.StorageDriver.ReadStream(ctx, path, offset)
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}
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// WriteStream stores the contents of the provided io.ReadCloser at a
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// location designated by the given path.
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// May be used to resume writing a stream by providing a nonzero offset.
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// The offset must be no larger than the CurrentSize for this path.
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func (r *regulator) WriteStream(ctx context.Context, path string, offset int64, reader io.Reader) (nn int64, err error) {
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r.enter()
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defer r.exit()
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return r.StorageDriver.WriteStream(ctx, path, offset, reader)
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}
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// Stat retrieves the FileInfo for the given path, including the current
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// size in bytes and the creation time.
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func (r *regulator) Stat(ctx context.Context, path string) (storagedriver.FileInfo, error) {
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r.enter()
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defer r.exit()
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return r.StorageDriver.Stat(ctx, path)
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}
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// List returns a list of the objects that are direct descendants of the
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//given path.
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func (r *regulator) List(ctx context.Context, path string) ([]string, error) {
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r.enter()
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defer r.exit()
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return r.StorageDriver.List(ctx, path)
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}
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// Move moves an object stored at sourcePath to destPath, removing the
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// original object.
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// Note: This may be no more efficient than a copy followed by a delete for
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// many implementations.
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func (r *regulator) Move(ctx context.Context, sourcePath string, destPath string) error {
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r.enter()
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defer r.exit()
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return r.StorageDriver.Move(ctx, sourcePath, destPath)
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}
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// Delete recursively deletes all objects stored at "path" and its subpaths.
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func (r *regulator) Delete(ctx context.Context, path string) error {
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r.enter()
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defer r.exit()
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return r.StorageDriver.Delete(ctx, path)
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}
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// URLFor returns a URL which may be used to retrieve the content stored at
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// the given path, possibly using the given options.
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// May return an ErrUnsupportedMethod in certain StorageDriver
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// implementations.
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func (r *regulator) URLFor(ctx context.Context, path string, options map[string]interface{}) (string, error) {
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r.enter()
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defer r.exit()
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return r.StorageDriver.URLFor(ctx, path, options)
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}
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@ -60,12 +60,12 @@ func FromParameters(parameters map[string]interface{}) *Driver {
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// New constructs a new Driver with a given rootDirectory
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func New(rootDirectory string) *Driver {
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fsDriver := &driver{rootDirectory: rootDirectory}
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return &Driver{
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baseEmbed: baseEmbed{
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Base: base.Base{
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StorageDriver: &driver{
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rootDirectory: rootDirectory,
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},
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StorageDriver: base.NewRegulator(fsDriver, 100),
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},
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},
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}
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