pitrou commented on a change in pull request #9265:
URL: https://github.com/apache/arrow/pull/9265#discussion_r561911098
##########
File path: cpp/src/arrow/util/io_util.cc
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@@ -1590,20 +1610,29 @@ Result<SignalHandler> SetSignalHandler(int signum,
const SignalHandler& handler)
namespace {
+int64_t GetPid() {
+#ifdef _WIN32
+ return GetCurrentProcessId();
+#else
+ return getpid();
+#endif
+}
+
std::mt19937_64 GetSeedGenerator() {
// Initialize Mersenne Twister PRNG with a true random seed.
+ // Make sure to mix in process id to minimize risks of clashes when parallel
testing.
#ifdef ARROW_VALGRIND
// Valgrind can crash, hang or enter an infinite loop on std::random_device,
// use a crude initializer instead.
- // Make sure to mix in process id to avoid clashes when parallel testing.
const uint8_t dummy = 0;
ARROW_UNUSED(dummy);
std::mt19937_64 seed_gen(reinterpret_cast<uintptr_t>(&dummy) ^
- static_cast<uintptr_t>(getpid()));
+ static_cast<uintptr_t>(GetPid()));
#else
std::random_device true_random;
std::mt19937_64 seed_gen(static_cast<uint64_t>(true_random()) ^
- (static_cast<uint64_t>(true_random()) << 32));
+ (static_cast<uint64_t>(true_random()) << 32) ^
+ (static_cast<uint64_t>(GetPid()) << 17));
Review comment:
Hmm, I don't know what I was thinking. Shifting is pointless here indeed.
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