Lock tcmalloc structures in a pthread_atfork hook.

third_party/tcmalloc/chromium/src/libc_override_osx.h

 // Copyright (c) 2011, Google Inc.
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
@@ skipping 66 matching lines @@
 #endif
 #include <gperftools/tcmalloc.h>
 
 #if !defined(__APPLE__)
 # error libc_override_glibc-osx.h is for OS X distributions only.
 #endif
 
 #include <AvailabilityMacros.h>
 #include <malloc/malloc.h>
 
+namespace tcmalloc {
+  void CentralCacheLockAll();
+  void CentralCacheUnlockAll();
+}
+
 // from AvailabilityMacros.h
 #if defined(MAC_OS_X_VERSION_10_6) && \
     MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_6
 extern "C" {
   // This function is only available on 10.6 (and later) but the
   // LibSystem headers do not use AvailabilityMacros.h to handle weak
   // importing automatically.  This prototype is a copy of the one in
   // <malloc/malloc.h> with the WEAK_IMPORT_ATTRBIUTE added.
   extern malloc_zone_t *malloc_default_purgeable_zone(void)
       WEAK_IMPORT_ATTRIBUTE;
@@ skipping 64 matching lines @@
   MallocExtension::instance()->GetStats(buffer, bufsize);
   fprintf(stdout, "%s", buffer);
   delete[] buffer;
 }
 
 void mi_log(malloc_zone_t *zone, void *address) {
   // I don't think we support anything like this
 }
 
 void mi_force_lock(malloc_zone_t *zone) {
-  // Hopefully unneeded by us!
+  tcmalloc::CentralCacheLockAll();
 }
 
 void mi_force_unlock(malloc_zone_t *zone) {
-  // Hopefully unneeded by us!
+  tcmalloc::CentralCacheUnlockAll();
 }
 
 void mi_statistics(malloc_zone_t *zone, malloc_statistics_t *stats) {
   // TODO(csilvers): figure out how to fill these out
   stats->blocks_in_use = 0;
   stats->size_in_use = 0;
   stats->max_size_in_use = 0;
   stats->size_allocated = 0;
 }
 
@@ skipping 80 matching lines @@
   // default zone makes the more recently registered zone the default
   // zone.  The default zone is then re-registered to ensure that
   // allocations made from it earlier will be handled correctly.
   // Things are not guaranteed to work that way, but it's how they work now.
   malloc_zone_t *default_zone = malloc_default_zone();
   malloc_zone_unregister(default_zone);
   malloc_zone_register(default_zone);
 }
 
 #endif  // TCMALLOC_LIBC_OVERRIDE_OSX_INL_H_