posix: set thread names

base/platform_thread_posix.cc

 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/platform_thread.h"
 
+#include <dlfcn.h>
 #include <errno.h>
 #include <sched.h>
 
 #if defined(OS_MACOSX)
 #include <mach/mach.h>
 #include <sys/resource.h>
 #include <algorithm>
-#else
+#endif
+
+#if defined(OS_LINUX)
+#include <sys/prctl.h>
 #include <sys/syscall.h>
 #include <unistd.h>
 #endif
 
+#include "base/logging.h"
+#include "base/safe_strerror_posix.h"
+
 #if defined(OS_MACOSX)
 namespace base {
 void InitThreading();
-}  // namespace
+}  // namespace base
 #endif
 
 static void* ThreadFunc(void* closure) {
   PlatformThread::Delegate* delegate =
       static_cast<PlatformThread::Delegate*>(closure);
   delegate->ThreadMain();
   return NULL;
 }
 
 // static
@@ skipping 23 matching lines @@
   sleep_time.tv_sec = duration_ms / 1000;
   duration_ms -= sleep_time.tv_sec * 1000;
 
   // Contains the portion of duration_ms < 1 sec.
   sleep_time.tv_nsec = duration_ms * 1000 * 1000;  // nanoseconds.
 
   while (nanosleep(&sleep_time, &remaining) == -1 && errno == EINTR)
     sleep_time = remaining;
 }
 
+// Linux SetName is currently disabled, as we need to distinguish between
+// helper threads (where it's ok to make this call) and the main thread
+// (where making this call renames our process, causing tools like killall
+// to stop working).
+#if 0 && defined(OS_LINUX)
 // static
 void PlatformThread::SetName(const char* name) {
-  // The POSIX standard does not provide for naming threads, and neither Linux
-  // nor Mac OS X (our two POSIX targets) provide any non-portable way of doing
-  // it either. (Some BSDs provide pthread_set_name_np but that isn't much of a
-  // consolation prize.)
-  // TODO(darin): decide whether stuffing the name in TLS or other in-memory
-  // structure would be useful for debugging or not.
+  // http://0pointer.de/blog/projects/name-your-threads.html
+
+  // glibc recently added support for pthread_setname_np, but it's not
+  // commonly available yet.  So test for it at runtime.
+  int (*dynamic_pthread_setname_np)(pthread_t, const char*);
+  *reinterpret_cast<void**>(&dynamic_pthread_setname_np) =
+      dlsym(RTLD_DEFAULT, "pthread_setname_np");
+
+  if (dynamic_pthread_setname_np) {
+    // This limit comes from glibc, which gets it from the kernel
+    // (TASK_COMM_LEN).
+    const int kMaxNameLength = 15;
+    std::string shortened_name = std::string(name).substr(0, kMaxNameLength);
+    int err = dynamic_pthread_setname_np(pthread_self(),
+                                         shortened_name.c_str());
+    if (err < 0)
+      LOG(ERROR) << "pthread_setname_np: " << safe_strerror(err);
+  } else {
+    // Implementing this function without glibc is simple enough.  (We
+    // don't do the name length clipping as above because it will be
+    // truncated by the callee (see TASK_COMM_LEN above).)
+    int err = prctl(PR_SET_NAME, name);
+    if (err < 0)
+      PLOG(ERROR) << "prctl(PR_SET_NAME)";
+  }
 }
+#elif defined(OS_MACOSX)
+// Mac is implemented in platform_thread_mac.mm.
+#else
+// static
+void PlatformThread::SetName(const char* name) {
+  // Leave it unimplemented.
+
+  // (This should be relatively simple to implement for the BSDs; I
+  // just don't have one handy to test the code on.)
+}
+#endif  // defined(OS_LINUX)
 
 namespace {
 
 bool CreateThread(size_t stack_size, bool joinable,
                   PlatformThread::Delegate* delegate,
                   PlatformThreadHandle* thread_handle) {
 #if defined(OS_MACOSX)
   base::InitThreading();
 #endif  // OS_MACOSX
 
@@ skipping 62 matching lines @@
 
   bool result = CreateThread(stack_size, false /* non-joinable thread */,
                              delegate, &unused);
   return result;
 }
 
 // static
 void PlatformThread::Join(PlatformThreadHandle thread_handle) {
   pthread_join(thread_handle, NULL);
 }