runtime/cgo: retry pthread_create on EAGAIN

Update #18146.

Change-Id: Ib447aabae9f203a8b61fb8c984b57d8e2bfe69c2
Reviewed-on: https://go-review.googlesource.com/33894
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

misc/cgo/test/cgo_unix_test.go

@@ -10,3 +10,4 @@ import "testing"
 
 func TestSigaltstack(t *testing.T) { testSigaltstack(t) }
 func TestSigprocmask(t *testing.T) { testSigprocmask(t) }
+func Test18146(t *testing.T)       { test18146(t) }

misc/cgo/test/issue18146.go

+// Copyright 2016 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.
+
+// +build !windows
+
+// Issue 18146: pthread_create failure during syscall.Exec.
+
+package cgotest
+
+import "C"
+
+import (
+	"bytes"
+	"crypto/md5"
+	"os"
+	"os/exec"
+	"runtime"
+	"syscall"
+	"testing"
+)
+
+func test18146(t *testing.T) {
+	switch runtime.GOOS {
+	case "darwin", "openbsd":
+		t.Skip("skipping on %s; issue 18146", runtime.GOOS)
+	}
+
+	attempts := 1000
+	threads := 4
+
+	if testing.Short() {
+		attempts = 100
+	}
+
+	if os.Getenv("test18146") == "exec" {
+		runtime.GOMAXPROCS(1)
+		for n := threads; n > 0; n-- {
+			go func() {
+				for {
+					_ = md5.Sum([]byte("Hello, !"))
+				}
+			}()
+		}
+		runtime.GOMAXPROCS(threads)
+		argv := append(os.Args, "-test.run=NoSuchTestExists")
+		if err := syscall.Exec(os.Args[0], argv, nil); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	var cmds []*exec.Cmd
+	defer func() {
+		for _, cmd := range cmds {
+			cmd.Process.Kill()
+		}
+	}()
+
+	args := append(append([]string(nil), os.Args[1:]...), "-test.run=Test18146")
+	for n := attempts; n > 0; n-- {
+		cmd := exec.Command(os.Args[0], args...)
+		cmd.Env = append(os.Environ(), "test18146=exec")
+		buf := bytes.NewBuffer(nil)
+		cmd.Stdout = buf
+		cmd.Stderr = buf
+		if err := cmd.Start(); err != nil {
+			t.Error(err)
+			return
+		}
+		cmds = append(cmds, cmd)
+	}
+
+	failures := 0
+	for _, cmd := range cmds {
+		err := cmd.Wait()
+		if err == nil {
+			continue
+		}
+
+		t.Errorf("syscall.Exec failed: %v\n%s", err, cmd.Stdout)
+		failures++
+	}
+
+	if failures > 0 {
+		t.Logf("Failed %v of %v attempts.", failures, len(cmds))
+	}
+}

src/runtime/cgo/gcc_darwin_386.c

@@ -6,6 +6,7 @@
 #include <pthread.h>
 #include <signal.h>
 #include "libcgo.h"
+#include "libcgo_unix.h"
 
 static void* threadentry(void*);
 static pthread_key_t k1;
@@ -123,7 +124,7 @@ _cgo_sys_thread_start(ThreadStart *ts)
 	pthread_attr_getstacksize(&attr, &size);
 	// Leave stacklo=0 and set stackhi=size; mstack will do the rest.
 	ts->g->stackhi = size;
-	err = pthread_create(&p, &attr, threadentry, ts);
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
 
 	pthread_sigmask(SIG_SETMASK, &oset, nil);
 

src/runtime/cgo/gcc_darwin_amd64.c

@@ -6,6 +6,7 @@
 #include <pthread.h>
 #include <signal.h>
 #include "libcgo.h"
+#include "libcgo_unix.h"
 
 static void* threadentry(void*);
 static pthread_key_t k1;
@@ -94,7 +95,7 @@ _cgo_sys_thread_start(ThreadStart *ts)
 	pthread_attr_getstacksize(&attr, &size);
 	// Leave stacklo=0 and set stackhi=size; mstack will do the rest.
 	ts->g->stackhi = size;
-	err = pthread_create(&p, &attr, threadentry, ts);
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
 
 	pthread_sigmask(SIG_SETMASK, &oset, nil);
 

src/runtime/cgo/gcc_darwin_arm.c

@@ -10,6 +10,7 @@
 #include <unistd.h>
 
 #include "libcgo.h"
+#include "libcgo_unix.h"
 
 #include <CoreFoundation/CFBundle.h>
 #include <CoreFoundation/CFString.h>
@@ -65,7 +66,7 @@ _cgo_sys_thread_start(ThreadStart *ts)
 	pthread_attr_getstacksize(&attr, &size);
 	// Leave stacklo=0 and set stackhi=size; mstack will do the rest.
 	ts->g->stackhi = size;
-	err = pthread_create(&p, &attr, threadentry, ts);
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
 
 	pthread_sigmask(SIG_SETMASK, &oset, nil);
 

src/runtime/cgo/gcc_darwin_arm64.c

@@ -11,6 +11,7 @@
 #include <stdlib.h>
 
 #include "libcgo.h"
+#include "libcgo_unix.h"
 
 #include <CoreFoundation/CFBundle.h>
 #include <CoreFoundation/CFString.h>
@@ -67,7 +68,7 @@ _cgo_sys_thread_start(ThreadStart *ts)
 	pthread_attr_getstacksize(&attr, &size);
 	// Leave stacklo=0 and set stackhi=size; mstack will do the rest.
 	ts->g->stackhi = size;
-	err = pthread_create(&p, &attr, threadentry, ts);
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
 
 	pthread_sigmask(SIG_SETMASK, &oset, nil);
 

src/runtime/cgo/gcc_dragonfly_amd64.c

@@ -8,6 +8,7 @@
 #include <signal.h>
 #include <string.h>
 #include "libcgo.h"
+#include "libcgo_unix.h"
 
 static void* threadentry(void*);
 static void (*setg_gcc)(void*);
@@ -42,7 +43,7 @@ _cgo_sys_thread_start(ThreadStart *ts)
 
 	// Leave stacklo=0 and set stackhi=size; mstack will do the rest.
 	ts->g->stackhi = size;
-	err = pthread_create(&p, &attr, threadentry, ts);
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
 
 	pthread_sigmask(SIG_SETMASK, &oset, nil);
 

src/runtime/cgo/gcc_freebsd_386.c

@@ -8,6 +8,7 @@
 #include <signal.h>
 #include <string.h>
 #include "libcgo.h"
+#include "libcgo_unix.h"
 
 static void* threadentry(void*);
 static void (*setg_gcc)(void*);
@@ -42,7 +43,7 @@ _cgo_sys_thread_start(ThreadStart *ts)
 	pthread_attr_getstacksize(&attr, &size);
 	// Leave stacklo=0 and set stackhi=size; mstack will do the rest.
 	ts->g->stackhi = size;
-	err = pthread_create(&p, &attr, threadentry, ts);
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
 
 	pthread_sigmask(SIG_SETMASK, &oset, nil);
 

src/runtime/cgo/gcc_freebsd_amd64.c

@@ -8,6 +8,7 @@
 #include <signal.h>
 #include <string.h>
 #include "libcgo.h"
+#include "libcgo_unix.h"
 
 static void* threadentry(void*);
 static void (*setg_gcc)(void*);
@@ -42,7 +43,7 @@ _cgo_sys_thread_start(ThreadStart *ts)
 
 	// Leave stacklo=0 and set stackhi=size; mstack will do the rest.
 	ts->g->stackhi = size;
-	err = pthread_create(&p, &attr, threadentry, ts);
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
 
 	pthread_sigmask(SIG_SETMASK, &oset, nil);
 

src/runtime/cgo/gcc_freebsd_arm.c

@@ -9,6 +9,7 @@
 #include <signal.h>
 #include <string.h>
 #include "libcgo.h"
+#include "libcgo_unix.h"
 
 #ifdef ARM_TP_ADDRESS
 // ARM_TP_ADDRESS is (ARM_VECTORS_HIGH + 0x1000) or 0xffff1000
@@ -58,7 +59,7 @@ _cgo_sys_thread_start(ThreadStart *ts)
 	pthread_attr_getstacksize(&attr, &size);
 	// Leave stacklo=0 and set stackhi=size; mstack will do the rest.
 	ts->g->stackhi = size;
-	err = pthread_create(&p, &attr, threadentry, ts);
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
 
 	pthread_sigmask(SIG_SETMASK, &oset, nil);
 

src/runtime/cgo/gcc_libinit.c

@@ -6,10 +6,13 @@
 // +build darwin dragonfly freebsd linux netbsd solaris
 
 #include <pthread.h>
+#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h> // strerror
+#include <time.h>
 #include "libcgo.h"
+#include "libcgo_unix.h"
 
 static pthread_cond_t runtime_init_cond = PTHREAD_COND_INITIALIZER;
 static pthread_mutex_t runtime_init_mu = PTHREAD_MUTEX_INITIALIZER;
@@ -21,7 +24,7 @@ static void (*cgo_context_function)(struct context_arg*);
 void
 x_cgo_sys_thread_create(void* (*func)(void*), void* arg) {
 	pthread_t p;
-	int err = pthread_create(&p, NULL, func, arg);
+	int err = _cgo_try_pthread_create(&p, NULL, func, arg);
 	if (err != 0) {
 		fprintf(stderr, "pthread_create failed: %s", strerror(err));
 		abort();
@@ -84,3 +87,23 @@ void (*(_cgo_get_context_function(void)))(struct context_arg*) {
 	pthread_mutex_unlock(&runtime_init_mu);
 	return ret;
 }
+
+// _cgo_try_pthread_create retries pthread_create if it fails with
+// EAGAIN.
+int
+_cgo_try_pthread_create(pthread_t* thread, const pthread_attr_t* attr, void* (*pfn)(void*), void* arg) {
+	int tries;
+	int err;
+	struct timespec ts;
+
+	for (tries = 0; tries < 20; tries++) {
+		err = pthread_create(thread, attr, pfn, arg);
+		if (err != EAGAIN) {
+			return err;
+		}
+		ts.tv_sec = 0;
+		ts.tv_nsec = (tries + 1) * 1000 * 1000; // Milliseconds.
+		nanosleep(&ts, nil);
+	}
+	return EAGAIN;
+}

src/runtime/cgo/gcc_linux_386.c

@@ -6,6 +6,7 @@
 #include <string.h>
 #include <signal.h>
 #include "libcgo.h"
+#include "libcgo_unix.h"
 
 static void *threadentry(void*);
 static void (*setg_gcc)(void*);
@@ -53,7 +54,7 @@ _cgo_sys_thread_start(ThreadStart *ts)
 	pthread_attr_getstacksize(&attr, &size);
 	// Leave stacklo=0 and set stackhi=size; mstack will do the rest.
 	ts->g->stackhi = size;
-	err = pthread_create(&p, &attr, threadentry, ts);
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
 
 	pthread_sigmask(SIG_SETMASK, &oset, nil);
 

src/runtime/cgo/gcc_linux_amd64.c

@@ -8,6 +8,7 @@
 #include <signal.h>
 #include <stdlib.h>
 #include "libcgo.h"
+#include "libcgo_unix.h"
 
 static void* threadentry(void*);
 static void (*setg_gcc)(void*);
@@ -70,7 +71,7 @@ _cgo_sys_thread_start(ThreadStart *ts)
 	pthread_attr_getstacksize(&attr, &size);
 	// Leave stacklo=0 and set stackhi=size; mstack will do the rest.
 	ts->g->stackhi = size;
-	err = pthread_create(&p, &attr, threadentry, ts);
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
 
 	pthread_sigmask(SIG_SETMASK, &oset, nil);
 

src/runtime/cgo/gcc_linux_arm.c

@@ -6,6 +6,7 @@
 #include <string.h>
 #include <signal.h>
 #include "libcgo.h"
+#include "libcgo_unix.h"
 
 static void *threadentry(void*);
 
@@ -33,7 +34,7 @@ _cgo_sys_thread_start(ThreadStart *ts)
 	pthread_attr_getstacksize(&attr, &size);
 	// Leave stacklo=0 and set stackhi=size; mstack will do the rest.
 	ts->g->stackhi = size;
-	err = pthread_create(&p, &attr, threadentry, ts);
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
 
 	pthread_sigmask(SIG_SETMASK, &oset, nil);
 

src/runtime/cgo/gcc_linux_arm64.c

@@ -6,6 +6,7 @@
 #include <string.h>
 #include <signal.h>
 #include "libcgo.h"
+#include "libcgo_unix.h"
 
 static void *threadentry(void*);
 
@@ -33,7 +34,7 @@ _cgo_sys_thread_start(ThreadStart *ts)
 	pthread_attr_getstacksize(&attr, &size);
 	// Leave stacklo=0 and set stackhi=size; mstack will do the rest.
 	ts->g->stackhi = size;
-	err = pthread_create(&p, &attr, threadentry, ts);
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
 
 	pthread_sigmask(SIG_SETMASK, &oset, nil);
 

src/runtime/cgo/gcc_linux_mips64x.c

@@ -10,6 +10,7 @@
 #include <string.h>
 #include <signal.h>
 #include "libcgo.h"
+#include "libcgo_unix.h"
 
 static void *threadentry(void*);
 
@@ -37,7 +38,7 @@ _cgo_sys_thread_start(ThreadStart *ts)
 	pthread_attr_getstacksize(&attr, &size);
 	// Leave stacklo=0 and set stackhi=size; mstack will do the rest.
 	ts->g->stackhi = size;
-	err = pthread_create(&p, &attr, threadentry, ts);
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
 
 	pthread_sigmask(SIG_SETMASK, &oset, nil);
 

src/runtime/cgo/gcc_linux_ppc64x.c

@@ -8,6 +8,7 @@
 #include <string.h>
 #include <signal.h>
 #include "libcgo.h"
+#include "libcgo_unix.h"
 
 static void *threadentry(void*);
 
@@ -43,7 +44,7 @@ _cgo_sys_thread_start(ThreadStart *ts)
 	pthread_attr_getstacksize(&attr, &size);
 	// Leave stacklo=0 and set stackhi=size; mstack will do the rest.
 	ts->g->stackhi = size;
-	err = pthread_create(&p, &attr, threadentry, ts);
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
 
 	pthread_sigmask(SIG_SETMASK, &oset, nil);
 

src/runtime/cgo/gcc_linux_s390x.c

@@ -6,6 +6,7 @@
 #include <string.h>
 #include <signal.h>
 #include "libcgo.h"
+#include "libcgo_unix.h"
 
 static void *threadentry(void*);
 
@@ -41,7 +42,7 @@ _cgo_sys_thread_start(ThreadStart *ts)
 	pthread_attr_getstacksize(&attr, &size);
 	// Leave stacklo=0 and set stackhi=size; mstack will do the rest.
 	ts->g->stackhi = size;
-	err = pthread_create(&p, &attr, threadentry, ts);
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
 
 	pthread_sigmask(SIG_SETMASK, &oset, nil);
 

src/runtime/cgo/gcc_netbsd_386.c

@@ -7,6 +7,7 @@
 #include <signal.h>
 #include <string.h>
 #include "libcgo.h"
+#include "libcgo_unix.h"
 
 static void* threadentry(void*);
 static void (*setg_gcc)(void*);
@@ -41,7 +42,7 @@ _cgo_sys_thread_start(ThreadStart *ts)
 	pthread_attr_getstacksize(&attr, &size);
 	// Leave stacklo=0 and set stackhi=size; mstack will do the rest.
 	ts->g->stackhi = size;
-	err = pthread_create(&p, &attr, threadentry, ts);
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
 
 	pthread_sigmask(SIG_SETMASK, &oset, nil);
 

src/runtime/cgo/gcc_netbsd_amd64.c

@@ -7,6 +7,7 @@
 #include <signal.h>
 #include <string.h>
 #include "libcgo.h"
+#include "libcgo_unix.h"
 
 static void* threadentry(void*);
 static void (*setg_gcc)(void*);
@@ -42,7 +43,7 @@ _cgo_sys_thread_start(ThreadStart *ts)
 
 	// Leave stacklo=0 and set stackhi=size; mstack will do the rest.
 	ts->g->stackhi = size;
-	err = pthread_create(&p, &attr, threadentry, ts);
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
 
 	pthread_sigmask(SIG_SETMASK, &oset, nil);
 

src/runtime/cgo/gcc_netbsd_arm.c

@@ -7,6 +7,7 @@
 #include <signal.h>
 #include <string.h>
 #include "libcgo.h"
+#include "libcgo_unix.h"
 
 static void *threadentry(void*);
 
@@ -42,7 +43,7 @@ _cgo_sys_thread_start(ThreadStart *ts)
 	pthread_attr_getstacksize(&attr, &size);
 	// Leave stacklo=0 and set stackhi=size; mstack will do the rest.
 	ts->g->stackhi = size;
-	err = pthread_create(&p, &attr, threadentry, ts);
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
 
 	pthread_sigmask(SIG_SETMASK, &oset, nil);
 

src/runtime/cgo/gcc_signal_darwin_armx.c

@@ -37,6 +37,7 @@
 #include <mach/thread_status.h>
 
 #include "libcgo.h"
+#include "libcgo_unix.h"
 
 uintptr_t x_cgo_panicmem;
 
@@ -201,7 +202,7 @@ darwin_arm_init_mach_exception_handler()
 	uintptr_t port_set = (uintptr_t)mach_exception_handler_port_set;
 	pthread_attr_init(&attr);
 	pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
-	ret = pthread_create(&thr, &attr, mach_exception_handler, (void*)port_set);
+	ret = _cgo_try_pthread_create(&thr, &attr, mach_exception_handler, (void*)port_set);
 
 	pthread_sigmask(SIG_SETMASK, &oset, nil);
 

src/runtime/cgo/gcc_solaris_amd64.c

@@ -7,6 +7,7 @@
 #include <signal.h>
 #include <ucontext.h>
 #include "libcgo.h"
+#include "libcgo_unix.h"
 
 static void* threadentry(void*);
 static void (*setg_gcc)(void*);
@@ -53,7 +54,7 @@ _cgo_sys_thread_start(ThreadStart *ts)
 		ts->g->stackhi = size;
 	}
 	pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
-	err = pthread_create(&p, &attr, threadentry, ts);
+	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
 
 	pthread_sigmask(SIG_SETMASK, &oset, nil);
 

src/runtime/cgo/libcgo_unix.h

+// Copyright 2016 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.
+
+/*
+ * Call pthread_create, retrying on EAGAIN.
+ */
+int _cgo_try_pthread_create(pthread_t*, const pthread_attr_t*, void* (*)(void*), void*);