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  1. Traffic Server
  2. TS-980

change client_session schedule from global to thread local, and reduce the try_locks in UnixNetVConnection::reenable


    • Type: Improvement
    • Status: Closed
    • Priority: Major
    • Resolution: Invalid
    • Affects Version/s: 3.1.0, 3.0.0
    • Fix Version/s: None
    • Component/s: Network, Performance
    • Labels:
    • Environment:



      I did some performance test on ats last days(disable cache, set share_server session 2, pure proxy mode), I did see significant improvement on low load, but it dropped rapidly when load is high. meanwhile, some stability problems happened. Through gdb, I found the client_session`s mutex can be acquired by two or more threads, I believe some schedules happened during the sm life_time. May be we need do some work to find these eventProcessor.schedules and change them to thread schedules.

      UnixVConnecton::reenable {
      if (nh->mutex->thread_holding == t) {
      // put into ready_list
      } else {
      MUTEX_TRY_LOCK(lock, nh->mutex, t);
      if (!lock)

      { // put into enable_list; }


      { // put into ready_list; }

      remove UnixNetVConnection::reenable try_lock operations, 3 reasons
      1. try_lock operation means obj allocation and deallocation operation. frequently
      2. try_lock hardly can lock the net-handler`s mutex.(net-handler is schedule by as soon as possible)
      3. try_lock should not acquire the net-handler`s mutex. That may lead more net io latency if it is an epoll event need to be processed in other threads. If it is not an epoll event(time event), I don`t think putting vc in ready_list has any advantage than in enable_list.

      may be we can change reenale function like this:
      UnixVConnecton::reenable {
      if (nh->mutex->thread_holding == t) {
      // put into ready_list;
      } else {
      // put into enable_list;

      my buddies, any advice?




            • Assignee:
              weijin weijin
              taorui weijin
            • Votes:
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              • Created: