1. 24 Oct, 2008 5 commits
  2. 23 Oct, 2008 8 commits
  3. 22 Oct, 2008 2 commits
  4. 21 Oct, 2008 11 commits
  5. 20 Oct, 2008 5 commits
  6. 17 Oct, 2008 2 commits
  7. 16 Oct, 2008 5 commits
  8. 15 Oct, 2008 2 commits
    • Davi Arnaut's avatar
      Bug#38477: my_pthread_setprio can change dispatch class on Solaris, not just priority · 459b8b3d
      Davi Arnaut authored
      The problem is that the function used by the server to increase
      the thread's priority (pthread_setschedparam) has the unintended
      side-effect of changing the calling thread scheduling policy,
      possibly overwriting a scheduling policy set by a sysadmin.
      
      The solution is to rely on the pthread_setschedprio function, if
      available, as it only changes the scheduling priority and does not
      change the scheduling policy. This function is usually available on
      Solaris and Linux, but it use won't work by default on Linux as the
      the default scheduling policy only accepts a static priority 0 -- this
      is acceptable for now as priority changing on Linux is broken anyway.
      459b8b3d
    • Davi Arnaut's avatar
      Bug#38941: fast mutexes in MySQL 5.1 have mutex contention when calling random() · 28f29b73
      Davi Arnaut authored
      The problem is that MySQL's 'fast' mutex implementation uses the
      random() routine to determine the spin delay. Unfortunately, the
      routine interface is not thead-safe and some implementations (eg:
      glibc) might use a internal lock to protect the RNG state, causing
      excessive locking contention if lots of threads are spinning on
      a MySQL's 'fast' mutex. The code was also misusing the value
      of the RAND_MAX macro, this macro represents the largest value
      that can be returned from the rand() function, not random().
      
      The solution is to use the quite simple Park-Miller random number
      generator. The initial seed is set to 1 because the previously used
      generator wasn't being seeded -- the initial seed is 1 if srandom()
      is not called.
      
      Futhermore, the 'fast' mutex implementation has several shortcomings
      and provides no measurable performance benefit. Therefore, its use is
      not recommended unless it provides directly measurable results.
      28f29b73