select {
			case <-stop:
				return
			case <-time.After(time.Millisecond * 100):
			}
		}
	}()
	defer close(stop)

	for i := 0; i < 1000; i++ {
		if !C.Ctid() {
			t.Fatalf("cgo has not locked OS thread")
		}
	}

			return err
		}
		defer func() {
			err := threadNS.Set() // switch back
			if err == nil {
				// Unlock the current thread only when we successfully switched back
				// to the original namespace; otherwise leave the thread locked which
				// will force the runtime to scrap the current thread, that is maybe
				// not as optimal but at least always safe to do.
				runtime.UnlockOSThread()
			}
		}()

		return toRun()

//   int i;
//   nts = argc;
//   t = calloc(nts, sizeof(pthread_t));
//   pthread_mutex_init(&mu, NULL);
//   for (i = 0; i < nts; i++) {
//     pthread_create(&t[i], NULL, aFn, NULL);
//   }
// }
//
// void cleanup(void) {
//   int i;
//   pthread_mutex_lock(&mu);
//   all_done = 1;
//   pthread_mutex_unlock(&mu);
//   for (i = 0; i < nts; i++) {
//     pthread_join(t[i], NULL);
//   }
//   pthread_mutex_destroy(&mu);

and then replacing all instances of C.zero with (*_C_zero).

Cgo's most interesting translation is for functions.  If xxx is a C
function, then cgo rewrites C.xxx into a new function _C_xxx that
calls the C xxx in a standard pthread.  The new function translates
its arguments, calls xxx, and translates the return value.

Translation of parameters and the return value follows the type
translation above except that arrays passed as parameters translate

	fn := z.decommissionCancelers[idx]
	if fn == nil {
		// canceling a decommission before it started return an error.
		return errDecommissionNotStarted
	}

	defer fn() // cancel any active thread.

	if z.poolMeta.DecommissionCancel(idx) {
		if err = z.poolMeta.save(ctx, z.serverPools); err != nil {
			return err
		}
		globalNotificationSys.ReloadPoolMeta(ctx)
	}

	return nil
}

// 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.

//go:build cgo && !windows

// Issue 18146: pthread_create failure during syscall.Exec.

package cgotest

import (
	"bytes"
	"crypto/md5"
	"os"
	"os/exec"
	"runtime"
	"syscall"
	"testing"
	"time"
)

func test18146(t *testing.T) {
	if testing.Short() {

	// which is the total amount of space, the total amount of free space, and the total
	// amount of free space available to the user that is associated with the calling thread.
	GetDiskFreeSpaceEx = kernel32.NewProc("GetDiskFreeSpaceExW")

	// GetDiskFreeSpace - https://msdn.microsoft.com/en-us/library/windows/desktop/aa364935(v=vs.85).aspx

When using cgo, Go must not assume that it owns all details of the
process. In particular it needs to coordinate with C in the use of
threads and thread-local storage. The runtime package declares a few
variables:

	var (
		iscgo             bool
		_cgo_init         unsafe.Pointer
		_cgo_thread_start unsafe.Pointer
	)

Any package using cgo imports "runtime/cgo", which provides

	if lockedOSThread() {
		t.Fatal("locked OS thread on entry to TestCallbackPanic")
	}
	defer func() {
		s := recover()
		if s == nil {
			t.Fatal("did not panic")
		}
		if s.(string) != "callback panic" {
			t.Fatal("wrong panic:", s)
		}
		if lockedOSThread() {
			t.Fatal("locked OS thread on exit from TestCallbackPanic")
		}
	}()
	nestedCall(func() { panic("callback panic") })