// Copyright 2009 The Go Authors. All rights reserved. // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. //go:build !js // +build !js package net import ( "errors" "fmt" "internal/testenv" "io" "net/internal/socktest" "os" "runtime" "sync" "testing" "time" ) var dialTimeoutTests = []struct { timeout time.Duration delta time.Duration // for deadline guard time.Duration max time.Duration }{ // Tests that dial timeouts, deadlines in the past work. {-5 * time.Second, 0, -5 * time.Second, 100 * time.Millisecond}, {0, -5 * time.Second, -5 * time.Second, 100 * time.Millisecond}, {-5 * time.Second, 5 * time.Second, -5 * time.Second, 100 * time.Millisecond}, // timeout over deadline {-1 << 63, 0, time.Second, 100 * time.Millisecond}, {0, -1 << 63, time.Second, 100 * time.Millisecond}, {50 * time.Millisecond, 0, 100 * time.Millisecond, time.Second}, {0, 50 * time.Millisecond, 100 * time.Millisecond, time.Second}, {50 * time.Millisecond, 5 * time.Second, 100 * time.Millisecond, time.Second}, // timeout over deadline } func TestDialTimeout(t *testing.T) { // Cannot use t.Parallel - modifies global hooks. origTestHookDialChannel := testHookDialChannel defer func() { testHookDialChannel = origTestHookDialChannel }() defer sw.Set(socktest.FilterConnect, nil) for i, tt := range dialTimeoutTests { switch runtime.GOOS { case "plan9", "windows": testHookDialChannel = func() { time.Sleep(tt.guard) } if runtime.GOOS == "plan9" { break } fallthrough default: sw.Set(socktest.FilterConnect, func(so *socktest.Status) (socktest.AfterFilter, error) { time.Sleep(tt.guard) return nil, errTimedout }) } ch := make(chan error) d := Dialer{Timeout: tt.timeout} if tt.delta != 0 { d.Deadline = time.Now().Add(tt.delta) } max := time.NewTimer(tt.max) defer max.Stop() go func() { // This dial never starts to send any TCP SYN // segment because of above socket filter and // test hook. c, err := d.Dial("tcp", "127.0.0.1:0") if err == nil { err = fmt.Errorf("unexpectedly established: tcp:%s->%s", c.LocalAddr(), c.RemoteAddr()) c.Close() } ch <- err }() select { case <-max.C: t.Fatalf("#%d: Dial didn't return in an expected time", i) case err := <-ch: if perr := parseDialError(err); perr != nil { t.Errorf("#%d: %v", i, perr) } if nerr, ok := err.(Error); !ok || !nerr.Timeout() { t.Fatalf("#%d: %v", i, err) } } } } var dialTimeoutMaxDurationTests = []struct { timeout time.Duration delta time.Duration // for deadline }{ // Large timeouts that will overflow an int64 unix nanos. {1<<63 - 1, 0}, {0, 1<<63 - 1}, } func TestDialTimeoutMaxDuration(t *testing.T) { if runtime.GOOS == "openbsd" { testenv.SkipFlaky(t, 15157) } ln, err := newLocalListener("tcp") if err != nil { t.Fatal(err) } defer ln.Close() for i, tt := range dialTimeoutMaxDurationTests { ch := make(chan error) max := time.NewTimer(250 * time.Millisecond) defer max.Stop() go func() { d := Dialer{Timeout: tt.timeout} if tt.delta != 0 { d.Deadline = time.Now().Add(tt.delta) } c, err := d.Dial(ln.Addr().Network(), ln.Addr().String()) if err == nil { c.Close() } ch <- err }() select { case <-max.C: t.Fatalf("#%d: Dial didn't return in an expected time", i) case err := <-ch: if perr := parseDialError(err); perr != nil { t.Error(perr) } if err != nil { t.Errorf("#%d: %v", i, err) } } } } var acceptTimeoutTests = []struct { timeout time.Duration xerrs [2]error // expected errors in transition }{ // Tests that accept deadlines in the past work, even if // there's incoming connections available. {-5 * time.Second, [2]error{os.ErrDeadlineExceeded, os.ErrDeadlineExceeded}}, {50 * time.Millisecond, [2]error{nil, os.ErrDeadlineExceeded}}, } func TestAcceptTimeout(t *testing.T) { testenv.SkipFlaky(t, 17948) t.Parallel() switch runtime.GOOS { case "plan9": t.Skipf("not supported on %s", runtime.GOOS) } ln, err := newLocalListener("tcp") if err != nil { t.Fatal(err) } defer ln.Close() var wg sync.WaitGroup for i, tt := range acceptTimeoutTests { if tt.timeout < 0 { wg.Add(1) go func() { defer wg.Done() d := Dialer{Timeout: 100 * time.Millisecond} c, err := d.Dial(ln.Addr().Network(), ln.Addr().String()) if err != nil { t.Error(err) return } c.Close() }() } if err := ln.(*TCPListener).SetDeadline(time.Now().Add(tt.timeout)); err != nil { t.Fatalf("$%d: %v", i, err) } for j, xerr := range tt.xerrs { for { c, err := ln.Accept() if xerr != nil { if perr := parseAcceptError(err); perr != nil { t.Errorf("#%d/%d: %v", i, j, perr) } if !isDeadlineExceeded(err) { t.Fatalf("#%d/%d: %v", i, j, err) } } if err == nil { c.Close() time.Sleep(10 * time.Millisecond) continue } break } } } wg.Wait() } func TestAcceptTimeoutMustReturn(t *testing.T) { t.Parallel() switch runtime.GOOS { case "plan9": t.Skipf("not supported on %s", runtime.GOOS) } ln, err := newLocalListener("tcp") if err != nil { t.Fatal(err) } defer ln.Close() max := time.NewTimer(time.Second) defer max.Stop() ch := make(chan error) go func() { if err := ln.(*TCPListener).SetDeadline(noDeadline); err != nil { t.Error(err) } if err := ln.(*TCPListener).SetDeadline(time.Now().Add(10 * time.Millisecond)); err != nil { t.Error(err) } c, err := ln.Accept() if err == nil { c.Close() } ch <- err }() select { case <-max.C: ln.Close() <-ch // wait for tester goroutine to stop t.Fatal("Accept didn't return in an expected time") case err := <-ch: if perr := parseAcceptError(err); perr != nil { t.Error(perr) } if !isDeadlineExceeded(err) { t.Fatal(err) } } } func TestAcceptTimeoutMustNotReturn(t *testing.T) { t.Parallel() switch runtime.GOOS { case "plan9": t.Skipf("not supported on %s", runtime.GOOS) } ln, err := newLocalListener("tcp") if err != nil { t.Fatal(err) } defer ln.Close() max := time.NewTimer(100 * time.Millisecond) defer max.Stop() ch := make(chan error) go func() { if err := ln.(*TCPListener).SetDeadline(time.Now().Add(-5 * time.Second)); err != nil { t.Error(err) } if err := ln.(*TCPListener).SetDeadline(noDeadline); err != nil { t.Error(err) } _, err := ln.Accept() ch <- err }() select { case err := <-ch: if perr := parseAcceptError(err); perr != nil { t.Error(perr) } t.Fatalf("expected Accept to not return, but it returned with %v", err) case <-max.C: ln.Close() <-ch // wait for tester goroutine to stop } } var readTimeoutTests = []struct { timeout time.Duration xerrs [2]error // expected errors in transition }{ // Tests that read deadlines work, even if there's data ready // to be read. {-5 * time.Second, [2]error{os.ErrDeadlineExceeded, os.ErrDeadlineExceeded}}, {50 * time.Millisecond, [2]error{nil, os.ErrDeadlineExceeded}}, } func TestReadTimeout(t *testing.T) { handler := func(ls *localServer, ln Listener) { c, err := ln.Accept() if err != nil { t.Error(err) return } c.Write([]byte("READ TIMEOUT TEST")) defer c.Close() } ls, err := newLocalServer("tcp") if err != nil { t.Fatal(err) } defer ls.teardown() if err := ls.buildup(handler); err != nil { t.Fatal(err) } c, err := Dial(ls.Listener.Addr().Network(), ls.Listener.Addr().String()) if err != nil { t.Fatal(err) } defer c.Close() for i, tt := range readTimeoutTests { if err := c.SetReadDeadline(time.Now().Add(tt.timeout)); err != nil { t.Fatalf("#%d: %v", i, err) } var b [1]byte for j, xerr := range tt.xerrs { for { n, err := c.Read(b[:]) if xerr != nil { if perr := parseReadError(err); perr != nil { t.Errorf("#%d/%d: %v", i, j, perr) } if !isDeadlineExceeded(err) { t.Fatalf("#%d/%d: %v", i, j, err) } } if err == nil { time.Sleep(tt.timeout / 3) continue } if n != 0 { t.Fatalf("#%d/%d: read %d; want 0", i, j, n) } break } } } } func TestReadTimeoutMustNotReturn(t *testing.T) { t.Parallel() switch runtime.GOOS { case "plan9": t.Skipf("not supported on %s", runtime.GOOS) } ln, err := newLocalListener("tcp") if err != nil { t.Fatal(err) } defer ln.Close() c, err := Dial(ln.Addr().Network(), ln.Addr().String()) if err != nil { t.Fatal(err) } defer c.Close() max := time.NewTimer(100 * time.Millisecond) defer max.Stop() ch := make(chan error) go func() { if err := c.SetDeadline(time.Now().Add(-5 * time.Second)); err != nil { t.Error(err) } if err := c.SetWriteDeadline(time.Now().Add(-5 * time.Second)); err != nil { t.Error(err) } if err := c.SetReadDeadline(noDeadline); err != nil { t.Error(err) } var b [1]byte _, err := c.Read(b[:]) ch <- err }() select { case err := <-ch: if perr := parseReadError(err); perr != nil { t.Error(perr) } t.Fatalf("expected Read to not return, but it returned with %v", err) case <-max.C: c.Close() err := <-ch // wait for tester goroutine to stop if perr := parseReadError(err); perr != nil { t.Error(perr) } if nerr, ok := err.(Error); !ok || nerr.Timeout() || nerr.Temporary() { t.Fatal(err) } } } var readFromTimeoutTests = []struct { timeout time.Duration xerrs [2]error // expected errors in transition }{ // Tests that read deadlines work, even if there's data ready // to be read. {-5 * time.Second, [2]error{os.ErrDeadlineExceeded, os.ErrDeadlineExceeded}}, {50 * time.Millisecond, [2]error{nil, os.ErrDeadlineExceeded}}, } func TestReadFromTimeout(t *testing.T) { ch := make(chan Addr) defer close(ch) handler := func(ls *localPacketServer, c PacketConn) { if dst, ok := <-ch; ok { c.WriteTo([]byte("READFROM TIMEOUT TEST"), dst) } } ls, err := newLocalPacketServer("udp") if err != nil { t.Fatal(err) } defer ls.teardown() if err := ls.buildup(handler); err != nil { t.Fatal(err) } host, _, err := SplitHostPort(ls.PacketConn.LocalAddr().String()) if err != nil { t.Fatal(err) } c, err := ListenPacket(ls.PacketConn.LocalAddr().Network(), JoinHostPort(host, "0")) if err != nil { t.Fatal(err) } defer c.Close() ch <- c.LocalAddr() for i, tt := range readFromTimeoutTests { if err := c.SetReadDeadline(time.Now().Add(tt.timeout)); err != nil { t.Fatalf("#%d: %v", i, err) } var b [1]byte for j, xerr := range tt.xerrs { for { n, _, err := c.ReadFrom(b[:]) if xerr != nil { if perr := parseReadError(err); perr != nil { t.Errorf("#%d/%d: %v", i, j, perr) } if !isDeadlineExceeded(err) { t.Fatalf("#%d/%d: %v", i, j, err) } } if err == nil { time.Sleep(tt.timeout / 3) continue } if nerr, ok := err.(Error); ok && nerr.Timeout() && n != 0 { t.Fatalf("#%d/%d: read %d; want 0", i, j, n) } break } } } } var writeTimeoutTests = []struct { timeout time.Duration xerrs [2]error // expected errors in transition }{ // Tests that write deadlines work, even if there's buffer // space available to write. {-5 * time.Second, [2]error{os.ErrDeadlineExceeded, os.ErrDeadlineExceeded}}, {10 * time.Millisecond, [2]error{nil, os.ErrDeadlineExceeded}}, } func TestWriteTimeout(t *testing.T) { t.Parallel() ln, err := newLocalListener("tcp") if err != nil { t.Fatal(err) } defer ln.Close() for i, tt := range writeTimeoutTests { c, err := Dial(ln.Addr().Network(), ln.Addr().String()) if err != nil { t.Fatal(err) } defer c.Close() if err := c.SetWriteDeadline(time.Now().Add(tt.timeout)); err != nil { t.Fatalf("#%d: %v", i, err) } for j, xerr := range tt.xerrs { for { n, err := c.Write([]byte("WRITE TIMEOUT TEST")) if xerr != nil { if perr := parseWriteError(err); perr != nil { t.Errorf("#%d/%d: %v", i, j, perr) } if !isDeadlineExceeded(err) { t.Fatalf("#%d/%d: %v", i, j, err) } } if err == nil { time.Sleep(tt.timeout / 3) continue } if n != 0 { t.Fatalf("#%d/%d: wrote %d; want 0", i, j, n) } break } } } } func TestWriteTimeoutMustNotReturn(t *testing.T) { t.Parallel() switch runtime.GOOS { case "plan9": t.Skipf("not supported on %s", runtime.GOOS) } ln, err := newLocalListener("tcp") if err != nil { t.Fatal(err) } defer ln.Close() c, err := Dial(ln.Addr().Network(), ln.Addr().String()) if err != nil { t.Fatal(err) } defer c.Close() max := time.NewTimer(100 * time.Millisecond) defer max.Stop() ch := make(chan error) go func() { if err := c.SetDeadline(time.Now().Add(-5 * time.Second)); err != nil { t.Error(err) } if err := c.SetReadDeadline(time.Now().Add(-5 * time.Second)); err != nil { t.Error(err) } if err := c.SetWriteDeadline(noDeadline); err != nil { t.Error(err) } var b [1]byte for { if _, err := c.Write(b[:]); err != nil { ch <- err break } } }() select { case err := <-ch: if perr := parseWriteError(err); perr != nil { t.Error(perr) } t.Fatalf("expected Write to not return, but it returned with %v", err) case <-max.C: c.Close() err := <-ch // wait for tester goroutine to stop if perr := parseWriteError(err); perr != nil { t.Error(perr) } if nerr, ok := err.(Error); !ok || nerr.Timeout() || nerr.Temporary() { t.Fatal(err) } } } var writeToTimeoutTests = []struct { timeout time.Duration xerrs [2]error // expected errors in transition }{ // Tests that write deadlines work, even if there's buffer // space available to write. {-5 * time.Second, [2]error{os.ErrDeadlineExceeded, os.ErrDeadlineExceeded}}, {10 * time.Millisecond, [2]error{nil, os.ErrDeadlineExceeded}}, } func TestWriteToTimeout(t *testing.T) { t.Parallel() c1, err := newLocalPacketListener("udp") if err != nil { t.Fatal(err) } defer c1.Close() host, _, err := SplitHostPort(c1.LocalAddr().String()) if err != nil { t.Fatal(err) } for i, tt := range writeToTimeoutTests { c2, err := ListenPacket(c1.LocalAddr().Network(), JoinHostPort(host, "0")) if err != nil { t.Fatal(err) } defer c2.Close() if err := c2.SetWriteDeadline(time.Now().Add(tt.timeout)); err != nil { t.Fatalf("#%d: %v", i, err) } for j, xerr := range tt.xerrs { for { n, err := c2.WriteTo([]byte("WRITETO TIMEOUT TEST"), c1.LocalAddr()) if xerr != nil { if perr := parseWriteError(err); perr != nil { t.Errorf("#%d/%d: %v", i, j, perr) } if !isDeadlineExceeded(err) { t.Fatalf("#%d/%d: %v", i, j, err) } } if err == nil { time.Sleep(tt.timeout / 3) continue } if n != 0 { t.Fatalf("#%d/%d: wrote %d; want 0", i, j, n) } break } } } } func TestReadTimeoutFluctuation(t *testing.T) { t.Parallel() ln, err := newLocalListener("tcp") if err != nil { t.Fatal(err) } defer ln.Close() c, err := Dial(ln.Addr().Network(), ln.Addr().String()) if err != nil { t.Fatal(err) } defer c.Close() max := time.NewTimer(time.Second) defer max.Stop() ch := make(chan error) go timeoutReceiver(c, 100*time.Millisecond, 50*time.Millisecond, 250*time.Millisecond, ch) select { case <-max.C: t.Fatal("Read took over 1s; expected 0.1s") case err := <-ch: if perr := parseReadError(err); perr != nil { t.Error(perr) } if !isDeadlineExceeded(err) { t.Fatal(err) } } } func TestReadFromTimeoutFluctuation(t *testing.T) { t.Parallel() c1, err := newLocalPacketListener("udp") if err != nil { t.Fatal(err) } defer c1.Close() c2, err := Dial(c1.LocalAddr().Network(), c1.LocalAddr().String()) if err != nil { t.Fatal(err) } defer c2.Close() max := time.NewTimer(time.Second) defer max.Stop() ch := make(chan error) go timeoutPacketReceiver(c2.(PacketConn), 100*time.Millisecond, 50*time.Millisecond, 250*time.Millisecond, ch) select { case <-max.C: t.Fatal("ReadFrom took over 1s; expected 0.1s") case err := <-ch: if perr := parseReadError(err); perr != nil { t.Error(perr) } if !isDeadlineExceeded(err) { t.Fatal(err) } } } func TestWriteTimeoutFluctuation(t *testing.T) { t.Parallel() switch runtime.GOOS { case "plan9": t.Skipf("not supported on %s", runtime.GOOS) } ln, err := newLocalListener("tcp") if err != nil { t.Fatal(err) } defer ln.Close() c, err := Dial(ln.Addr().Network(), ln.Addr().String()) if err != nil { t.Fatal(err) } defer c.Close() d := time.Second if iOS() { d = 3 * time.Second // see golang.org/issue/10775 } max := time.NewTimer(d) defer max.Stop() ch := make(chan error) go timeoutTransmitter(c, 100*time.Millisecond, 50*time.Millisecond, 250*time.Millisecond, ch) select { case <-max.C: t.Fatalf("Write took over %v; expected 0.1s", d) case err := <-ch: if perr := parseWriteError(err); perr != nil { t.Error(perr) } if !isDeadlineExceeded(err) { t.Fatal(err) } } } func TestVariousDeadlines(t *testing.T) { t.Parallel() testVariousDeadlines(t) } func TestVariousDeadlines1Proc(t *testing.T) { // Cannot use t.Parallel - modifies global GOMAXPROCS. if testing.Short() { t.Skip("skipping in short mode") } defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(1)) testVariousDeadlines(t) } func TestVariousDeadlines4Proc(t *testing.T) { // Cannot use t.Parallel - modifies global GOMAXPROCS. if testing.Short() { t.Skip("skipping in short mode") } defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(4)) testVariousDeadlines(t) } type neverEnding byte func (b neverEnding) Read(p []byte) (int, error) { for i := range p { p[i] = byte(b) } return len(p), nil } func testVariousDeadlines(t *testing.T) { if runtime.GOOS == "plan9" { t.Skip("skipping test on plan9; see golang.org/issue/26945") } type result struct { n int64 err error d time.Duration } handler := func(ls *localServer, ln Listener) { for { c, err := ln.Accept() if err != nil { break } c.Read(make([]byte, 1)) // wait for client to close connection c.Close() } } ls, err := newLocalServer("tcp") if err != nil { t.Fatal(err) } defer ls.teardown() if err := ls.buildup(handler); err != nil { t.Fatal(err) } for _, timeout := range []time.Duration{ 1 * time.Nanosecond, 2 * time.Nanosecond, 5 * time.Nanosecond, 50 * time.Nanosecond, 100 * time.Nanosecond, 200 * time.Nanosecond, 500 * time.Nanosecond, 750 * time.Nanosecond, 1 * time.Microsecond, 5 * time.Microsecond, 25 * time.Microsecond, 250 * time.Microsecond, 500 * time.Microsecond, 1 * time.Millisecond, 5 * time.Millisecond, 100 * time.Millisecond, 250 * time.Millisecond, 500 * time.Millisecond, 1 * time.Second, } { numRuns := 3 if testing.Short() { numRuns = 1 if timeout > 500*time.Microsecond { continue } } for run := 0; run < numRuns; run++ { name := fmt.Sprintf("%v %d/%d", timeout, run, numRuns) t.Log(name) tooSlow := time.NewTimer(5 * time.Second) defer tooSlow.Stop() c, err := Dial(ls.Listener.Addr().Network(), ls.Listener.Addr().String()) if err != nil { t.Fatal(err) } ch := make(chan result, 1) go func() { t0 := time.Now() if err := c.SetDeadline(t0.Add(timeout)); err != nil { t.Error(err) } n, err := io.Copy(io.Discard, c) dt := time.Since(t0) c.Close() ch <- result{n, err, dt} }() select { case res := <-ch: if nerr, ok := res.err.(Error); ok && nerr.Timeout() { t.Logf("%v: good timeout after %v; %d bytes", name, res.d, res.n) } else { t.Fatalf("%v: Copy = %d, %v; want timeout", name, res.n, res.err) } case <-tooSlow.C: t.Fatalf("%v: client stuck in Dial+Copy", name) } } } } // TestReadWriteProlongedTimeout tests concurrent deadline // modification. Known to cause data races in the past. func TestReadWriteProlongedTimeout(t *testing.T) { t.Parallel() switch runtime.GOOS { case "plan9": t.Skipf("not supported on %s", runtime.GOOS) } handler := func(ls *localServer, ln Listener) { c, err := ln.Accept() if err != nil { t.Error(err) return } defer c.Close() var wg sync.WaitGroup wg.Add(2) go func() { defer wg.Done() var b [1]byte for { if err := c.SetReadDeadline(time.Now().Add(time.Hour)); err != nil { if perr := parseCommonError(err); perr != nil { t.Error(perr) } t.Error(err) return } if _, err := c.Read(b[:]); err != nil { if perr := parseReadError(err); perr != nil { t.Error(perr) } return } } }() go func() { defer wg.Done() var b [1]byte for { if err := c.SetWriteDeadline(time.Now().Add(time.Hour)); err != nil { if perr := parseCommonError(err); perr != nil { t.Error(perr) } t.Error(err) return } if _, err := c.Write(b[:]); err != nil { if perr := parseWriteError(err); perr != nil { t.Error(perr) } return } } }() wg.Wait() } ls, err := newLocalServer("tcp") if err != nil { t.Fatal(err) } defer ls.teardown() if err := ls.buildup(handler); err != nil { t.Fatal(err) } c, err := Dial(ls.Listener.Addr().Network(), ls.Listener.Addr().String()) if err != nil { t.Fatal(err) } defer c.Close() var b [1]byte for i := 0; i < 1000; i++ { c.Write(b[:]) c.Read(b[:]) } } func TestReadWriteDeadlineRace(t *testing.T) { t.Parallel() N := 1000 if testing.Short() { N = 50 } ln, err := newLocalListener("tcp") if err != nil { t.Fatal(err) } defer ln.Close() c, err := Dial(ln.Addr().Network(), ln.Addr().String()) if err != nil { t.Fatal(err) } defer c.Close() var wg sync.WaitGroup wg.Add(3) go func() { defer wg.Done() tic := time.NewTicker(2 * time.Microsecond) defer tic.Stop() for i := 0; i < N; i++ { if err := c.SetReadDeadline(time.Now().Add(2 * time.Microsecond)); err != nil { if perr := parseCommonError(err); perr != nil { t.Error(perr) } break } if err := c.SetWriteDeadline(time.Now().Add(2 * time.Microsecond)); err != nil { if perr := parseCommonError(err); perr != nil { t.Error(perr) } break } <-tic.C } }() go func() { defer wg.Done() var b [1]byte for i := 0; i < N; i++ { c.Read(b[:]) // ignore possible timeout errors } }() go func() { defer wg.Done() var b [1]byte for i := 0; i < N; i++ { c.Write(b[:]) // ignore possible timeout errors } }() wg.Wait() // wait for tester goroutine to stop } // Issue 35367. func TestConcurrentSetDeadline(t *testing.T) { ln, err := newLocalListener("tcp") if err != nil { t.Fatal(err) } defer ln.Close() const goroutines = 8 const conns = 10 const tries = 100 var c [conns]Conn for i := 0; i < conns; i++ { c[i], err = Dial(ln.Addr().Network(), ln.Addr().String()) if err != nil { t.Fatal(err) } defer c[i].Close() } var wg sync.WaitGroup wg.Add(goroutines) now := time.Now() for i := 0; i < goroutines; i++ { go func(i int) { defer wg.Done() // Make the deadlines steadily earlier, // to trigger runtime adjusttimers calls. for j := tries; j > 0; j-- { for k := 0; k < conns; k++ { c[k].SetReadDeadline(now.Add(2*time.Hour + time.Duration(i*j*k)*time.Second)) c[k].SetWriteDeadline(now.Add(1*time.Hour + time.Duration(i*j*k)*time.Second)) } } }(i) } wg.Wait() } // isDeadlineExceeded reports whether err is or wraps os.ErrDeadlineExceeded. // We also check that the error implements net.Error, and that the // Timeout method returns true. func isDeadlineExceeded(err error) bool { nerr, ok := err.(Error) if !ok { return false } if !nerr.Timeout() { return false } if !errors.Is(err, os.ErrDeadlineExceeded) { return false } return true }