[net] net/http2: pool transport gzip readers
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Gerrit Bot (Gerrit)
Oct 8, 2025, 12:43:16 PM (7 days ago) Oct 8
to goph...@pubsubhelper.golang.org, Alexander Yastrebov, golang-co...@googlegroups.com
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Commit message
net/http2: pool transport gzip readers
This is a copy of the CL 510255 with the difference that it preserves use of fs.ErrClosed when reading after close.
Updates golang/go#61353
Change-Id: I0fdc0c0a5947d27dcc615e5bcf4d4620c2c95d9e
GitHub-Last-Rev: 5e48e8141fb1658503e056d69b109a03fb685a03
GitHub-Pull-Request: golang/net#239
Change diff
diff --git a/http2/transport.go b/http2/transport.go
index be759b6..1965913 100644
--- a/http2/transport.go
+++ b/http2/transport.go
@@ -9,6 +9,7 @@
import (
"bufio"
"bytes"
+ "compress/flate"
"compress/gzip"
"context"
"crypto/rand"
@@ -3076,35 +3077,102 @@
func (rt erringRoundTripper) RoundTripErr() error { return rt.err }
func (rt erringRoundTripper) RoundTrip(*http.Request) (*http.Response, error) { return nil, rt.err }
+var errConcurrentReadOnResBody = errors.New("http2: concurrent read on response body")
+
// gzipReader wraps a response body so it can lazily
-// call gzip.NewReader on the first call to Read
+// get gzip.Reader from the pool on the first call to Read.
+// After Close is called it puts gzip.Reader to the pool immediately
+// if there is no Read in progress or later when Read completes.
type gzipReader struct {
_ incomparable
body io.ReadCloser // underlying Response.Body
- zr *gzip.Reader // lazily-initialized gzip reader
- zerr error // sticky error
+ mu sync.Mutex // guards zr and zerr
+ zr *gzip.Reader // stores gzip reader from the pool between reads
+ zerr error // sticky gzip reader init error or sentinel value to detect concurrent read and read after close
+}
+
+type eofReader struct{}
+
+func (eofReader) Read([]byte) (int, error) { return 0, io.EOF }
+func (eofReader) ReadByte() (byte, error) { return 0, io.EOF }
+
+var gzipPool = sync.Pool{New: func() any { return new(gzip.Reader) }}
+
+// gzipPoolGet gets a gzip.Reader from the pool and resets it to read from r.
+func gzipPoolGet(r io.Reader) (*gzip.Reader, error) {
+ zr := gzipPool.Get().(*gzip.Reader)
+ if err := zr.Reset(r); err != nil {
+ gzipPoolPut(zr)
+ return nil, err
+ }
+ return zr, nil
+}
+
+// gzipPoolPut puts a gzip.Reader back into the pool.
+func gzipPoolPut(zr *gzip.Reader) {
+ // Reset will allocate bufio.Reader if we pass it anything
+ // other than a flate.Reader, so ensure that it's getting one.
+ var r flate.Reader = eofReader{}
+ zr.Reset(r)
+ gzipPool.Put(zr)
+}
+
+// acquire returns a gzip.Reader for reading response body.
+// The reader must be released after use.
+func (gz *gzipReader) acquire() (*gzip.Reader, error) {
+ gz.mu.Lock()
+ defer gz.mu.Unlock()
+ if gz.zerr != nil {
+ return nil, gz.zerr
+ }
+ if gz.zr == nil {
+ gz.zr, gz.zerr = gzipPoolGet(gz.body)
+ if gz.zerr != nil {
+ return nil, gz.zerr
+ }
+ }
+ ret := gz.zr
+ gz.zr, gz.zerr = nil, errConcurrentReadOnResBody
+ return ret, nil
+}
+
+// release returns the gzip.Reader to the pool if Close was called during Read.
+func (gz *gzipReader) release(zr *gzip.Reader) {
+ gz.mu.Lock()
+ defer gz.mu.Unlock()
+ if gz.zerr == errConcurrentReadOnResBody {
+ gz.zr, gz.zerr = zr, nil
+ } else { // fs.ErrClosed
+ gzipPoolPut(zr)
+ }
+}
+
+// close returns the gzip.Reader to the pool immediately or
+// signals release to do so after Read completes.
+func (gz *gzipReader) close() {
+ gz.mu.Lock()
+ defer gz.mu.Unlock()
+ if gz.zerr == nil && gz.zr != nil {
+ gzipPoolPut(gz.zr)
+ gz.zr = nil
+ }
+ gz.zerr = fs.ErrClosed
}
func (gz *gzipReader) Read(p []byte) (n int, err error) {
- if gz.zerr != nil {
- return 0, gz.zerr
+ zr, err := gz.acquire()
+ if err != nil {
+ return 0, err
}
- if gz.zr == nil {
- gz.zr, err = gzip.NewReader(gz.body)
- if err != nil {
- gz.zerr = err
- return 0, err
- }
- }
- return gz.zr.Read(p)
+ defer gz.release(zr)
+
+ return zr.Read(p)
}
func (gz *gzipReader) Close() error {
- if err := gz.body.Close(); err != nil {
- return err
- }
- gz.zerr = fs.ErrClosed
- return nil
+ gz.close()
+
+ return gz.body.Close()
}
type errorReader struct{ err error }
Change information
Files:
- M http2/transport.go
Change size: M
Delta: 1 file changed, 86 insertions(+), 18 deletions(-)
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Gopher Robot (Gerrit)
Oct 8, 2025, 12:43:18 PM (7 days ago) Oct 8
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Gopher Robot added 1 comment![]( "Open in Gerrit")
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File-level comment, Patchset 1 (Latest):
Gopher Robot . unresolved
I spotted some possible problems with your PR:
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Alexander Yastrebov (Gerrit)
Oct 8, 2025, 12:49:09 PM (7 days ago) Oct 8
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Alexander Yastrebov added 1 comment![]( "Open in Gerrit")
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Gopher Robot . resolved
I spotted some possible problems with your PR:
1. You have a long 115 character line in the commit message body. Please add line breaks to long lines that should be wrapped. Lines in the commit message body should be wrapped at ~76 characters unless needed for things like URLs or tables. (Note: GitHub might render long lines as soft-wrapped, so double-check in the Gerrit commit message shown above.)Please address any problems by updating the GitHub PR.
When complete, mark this comment as 'Done' and click the [blue 'Reply' button](https://go.dev/wiki/GerritBot#i-left-a-reply-to-a-comment-in-gerrit-but-no-one-but-me-can-see-it) above. These findings are based on heuristics; if a finding does not apply, briefly reply here saying so.
To update the commit title or commit message body shown here in Gerrit, you must edit the GitHub PR title and PR description (the first comment) in the GitHub web interface using the 'Edit' button or 'Edit' menu entry there. Note: pushing a new commit to the PR will not automatically update the commit message used by Gerrit.
For more details, see:
- [how to update commit messages](https://go.dev/wiki/GerritBot/#how-does-gerritbot-determine-the-final-commit-message) for PRs imported into Gerrit.
- the Go project's [conventions for commit messages](https://go.dev/doc/contribute#commit_messages) that you should follow.
(In general for Gerrit code reviews, the change author is expected to [log in to Gerrit](https://go-review.googlesource.com/login/) with a Gmail or other Google account and then close out each piece of feedback by marking it as 'Done' if implemented as suggested or otherwise reply to each review comment. See the [Review](https://go.dev/doc/contribute#review) section of the Contributing Guide for details.)
Alexander Yastrebov
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Oct 8, 2025, 12:51:08 PM (7 days ago) Oct 8
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Oct 8, 2025, 4:33:03 PM (7 days ago) Oct 8
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Line 11, Patchset 2 (Latest):
Sean Liao . unresolved
Since they're different code paths, I think this needs a benchmark
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Sean Liao . resolved
Since they're different code paths, I think this needs a benchmark
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Change information
Commit message:
net/http2: pool transport gzip readers
This is a copy of the CL 510255 with the difference that
it preserves use of fs.ErrClosed when reading after close.
goos: darwin
goarch: arm64
pkg: golang.org/x/net/http2
cpu: Apple M4
│ HEAD~1 │ HEAD │
│ sec/op │ sec/op vs base │
ClientGzip-10 752.8µ ± 1% 750.7µ ± 2% ~ (p=0.393 n=10)
│ HEAD~1 │ HEAD │
│ B/op │ B/op vs base │
ClientGzip-10 75.49Ki ± 0% 33.98Ki ± 3% -54.99% (p=0.000 n=10)
│ HEAD~1 │ HEAD │
│ allocs/op │ allocs/op vs base │
ClientGzip-10 705.0 ± 0% 698.5 ± 0% -0.92% (p=0.000 n=10)
Updates golang/go#61353
Change-Id: I0fdc0c0a5947d27dcc615e5bcf4d4620c2c95d9e
GitHub-Last-Rev: 4d04dc93f37ec6cdaf36c6851250806166f4e8c1
GitHub-Pull-Request: golang/net#239
Reviewed-on: https://go-review.googlesource.com/c/net/+/710235
Reviewed-by: Sean Liao <se...@liao.dev>
Reviewed-by: Michael Pratt <mpr...@google.com>
LUCI-TryBot-Result: Go LUCI <golang...@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Damien Neil <dn...@google.com>
Auto-Submit: Damien Neil <dn...@google.com>
Files:
- M http2/transport.go
- M http2/transport_test.go
Change size: M
Delta: 2 files changed, 138 insertions(+), 18 deletions(-)
Branch: refs/heads/master
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