Fix issue http://code.google.com/p/v8/issues/detail?id=58:...

src/platform-macos.cc

 // Copyright 2006-2008 the V8 project authors. 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
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 55 matching lines @@
   if (-1.0 < x && x < 0.0) {
     return -0.0;
   } else {
     return ceil(x);
   }
 }
 
 
 void OS::Setup() {
   // Seed the random number generator.
-  srandom(static_cast<unsigned int>(TimeCurrentMillis()));
+  // Convert the current time to a 64-bit integer first, before converting it
+  // to an unsigned. Going directly will cause an overflow and the seed to be
+  // set to all ones. The seed will be identical for different instances that
+  // call this setup code within the same millisecond.
+  uint64_t seed = static_cast<uint64_t>(TimeCurrentMillis());
+  srandom(static_cast<unsigned int>(seed));
 }
 
 
 int OS::GetUserTime(uint32_t* secs,  uint32_t* usecs) {
   struct rusage usage;
 
   if (getrusage(RUSAGE_SELF, &usage) < 0) return -1;
   *secs = usage.ru_utime.tv_sec;
   *usecs = usage.ru_utime.tv_usec;
   return 0;
@@ skipping 517 matching lines @@
   }
 
   // This sampler is no longer the active sampler.
   active_sampler_ = NULL;
   active_ = false;
 }
 
 #endif  // ENABLE_LOGGING_AND_PROFILING
 
 } }  // namespace v8::internal