qsort() isn't thread safe

Solution Verified - Updated -


  • In RHEL5, a multi-threaded application using the qsort() function may dump core with a floating point exception. We found out that RHEL6 has the same problem.
  • The qsort() function is not listed as "need not be thread-safe" functions in POSIX.1-2008, "2.9.1 Thread-Safety". So it shall be thread-safe and be safely available in the multi-threaded application.
  • This problem is already fixed in the latest upstream glibc(<= 2.12.2).


  • Red Hat Enterprise Linux 5.8
  • glibc-2.5-81(RHEL5.8)
  • Red Hat Enterprise Linux 6.3
  • glibc-2.12-1.80(RHEL6.3)

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