https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94087
Bug ID: 94087
Summary: std::random_device often fails when used from multiple
threads
Product: gcc
Version: 9.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: coryan+gccbugzilla at google dot com
Target Milestone: ---
Created attachment 47995
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=47995&action=edit
A program to reproduce the problem.
Creating and using a `std::random_device` object fails when used from multiple
threads. A `std::exception` exception is throw with the message "random_device:
rdseed failed", probably from this point in the code:
https://github.com/gcc-mirror/gcc/blob/2a4c59d9aa6b1018fa8f86dd8c0573c1fed3f199/libstdc%2B%2B-v3/src/c%2B%2B11/random.cc#L108
The problem is easy to reproduce, compile the attached program and run it, it
fails every time. I guess any version where __GLIBCXX__ >= 20200128 would have
this problem.
I just compiled with:
g++ -std=c++17 -pthread -o /tmp/repro-rdseed repro-rdseed.cc
and then run the program using:
/tmp/repro-rdseed
The program exits with 0 on success, 1 on failure, and prints some explanatory
messages (and some version numbers).
The bug *is* present on openSUSE/Tumbleweed, where the compiler reports:
g++ (SUSE Linux) 9.2.1 20200128 [revision
83f65674e78d97d27537361de1a9d74067ff228d]
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
The bug is *not* present on on Fedora:31 where the compiler reports:
g++ (GCC) 9.2.1 20190827 (Red Hat 9.2.1-1)
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
PS: Apologies if I get my version numbers wrong, I am used to using binary
distributions, have not compiled GCC from source in 2 decades or so.
