From 708c714dafd49bb2440166876eb2b8486b452b80 Mon Sep 17 00:00:00 2001 From: jmasa Date: Fri, 1 Feb 2013 17:02:36 -0800 Subject: [PATCH] 7189971: Implement CMSWaitDuration for non-incremental mode of CMS Reviewed-by: jmasa, johnc, ysr Contributed-by: michal@frajt.eu --- .../concurrentMarkSweepThread.cpp | 94 ++++++++++++++++++- .../concurrentMarkSweepThread.hpp | 6 ++ src/share/vm/runtime/globals.hpp | 4 + 3 files changed, 99 insertions(+), 5 deletions(-) diff --git a/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.cpp b/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.cpp index c8e6e5185..7bc1c1ea9 100644 --- a/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.cpp +++ b/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.cpp @@ -300,8 +300,7 @@ void ConcurrentMarkSweepThread::desynchronize(bool is_cms_thread) { } } -// Wait until the next synchronous GC, a concurrent full gc request, -// or a timeout, whichever is earlier. +// Wait until any cms_lock event void ConcurrentMarkSweepThread::wait_on_cms_lock(long t_millis) { MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); @@ -315,15 +314,100 @@ void ConcurrentMarkSweepThread::wait_on_cms_lock(long t_millis) { "Should not be set"); } +// Wait until the next synchronous GC, a concurrent full gc request, +// or a timeout, whichever is earlier. +void ConcurrentMarkSweepThread::wait_on_cms_lock_for_scavenge(long t_millis) { + // Wait time in millis or 0 value representing infinite wait for a scavenge + assert(t_millis >= 0, "Wait time for scavenge should be 0 or positive"); + + GenCollectedHeap* gch = GenCollectedHeap::heap(); + double start_time_secs = os::elapsedTime(); + double end_time_secs = start_time_secs + (t_millis / ((double) MILLIUNITS)); + + // Total collections count before waiting loop + unsigned int before_count; + { + MutexLockerEx hl(Heap_lock, Mutex::_no_safepoint_check_flag); + before_count = gch->total_collections(); + } + + unsigned int loop_count = 0; + + while(!_should_terminate) { + double now_time = os::elapsedTime(); + long wait_time_millis; + + if(t_millis != 0) { + // New wait limit + wait_time_millis = (long) ((end_time_secs - now_time) * MILLIUNITS); + if(wait_time_millis <= 0) { + // Wait time is over + break; + } + } else { + // No wait limit, wait if necessary forever + wait_time_millis = 0; + } + + // Wait until the next event or the remaining timeout + { + MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag); + + if (_should_terminate || _collector->_full_gc_requested) { + return; + } + set_CMS_flag(CMS_cms_wants_token); // to provoke notifies + assert(t_millis == 0 || wait_time_millis > 0, "Sanity"); + CGC_lock->wait(Mutex::_no_safepoint_check_flag, wait_time_millis); + clear_CMS_flag(CMS_cms_wants_token); + assert(!CMS_flag_is_set(CMS_cms_has_token | CMS_cms_wants_token), + "Should not be set"); + } + + // Extra wait time check before entering the heap lock to get the collection count + if(t_millis != 0 && os::elapsedTime() >= end_time_secs) { + // Wait time is over + break; + } + + // Total collections count after the event + unsigned int after_count; + { + MutexLockerEx hl(Heap_lock, Mutex::_no_safepoint_check_flag); + after_count = gch->total_collections(); + } + + if(before_count != after_count) { + // There was a collection - success + break; + } + + // Too many loops warning + if(++loop_count == 0) { + warning("wait_on_cms_lock_for_scavenge() has looped %u times", loop_count - 1); + } + } +} + void ConcurrentMarkSweepThread::sleepBeforeNextCycle() { while (!_should_terminate) { if (CMSIncrementalMode) { icms_wait(); + if(CMSWaitDuration >= 0) { + // Wait until the next synchronous GC, a concurrent full gc + // request or a timeout, whichever is earlier. + wait_on_cms_lock_for_scavenge(CMSWaitDuration); + } return; } else { - // Wait until the next synchronous GC, a concurrent full gc - // request or a timeout, whichever is earlier. - wait_on_cms_lock(CMSWaitDuration); + if(CMSWaitDuration >= 0) { + // Wait until the next synchronous GC, a concurrent full gc + // request or a timeout, whichever is earlier. + wait_on_cms_lock_for_scavenge(CMSWaitDuration); + } else { + // Wait until any cms_lock event or check interval not to call shouldConcurrentCollect permanently + wait_on_cms_lock(CMSCheckInterval); + } } // Check if we should start a CMS collection cycle if (_collector->shouldConcurrentCollect()) { diff --git a/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp b/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp index f59ce4598..5c3f01583 100644 --- a/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp +++ b/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp @@ -130,6 +130,12 @@ class ConcurrentMarkSweepThread: public ConcurrentGCThread { // A concurrent full gc request terminates the wait. void wait_on_cms_lock(long t_millis); + // Wait on CMS lock until the next synchronous GC + // or given timeout, whichever is earlier. A timeout value + // of 0 indicates that there is no upper bound on the wait time. + // A concurrent full gc request terminates the wait. + void wait_on_cms_lock_for_scavenge(long t_millis); + // The CMS thread will yield during the work portion of its cycle // only when requested to. Both synchronous and asychronous requests // are provided: diff --git a/src/share/vm/runtime/globals.hpp b/src/share/vm/runtime/globals.hpp index 8a0be8f8a..ef41b3509 100644 --- a/src/share/vm/runtime/globals.hpp +++ b/src/share/vm/runtime/globals.hpp @@ -1751,6 +1751,10 @@ class CommandLineFlags { manageable(intx, CMSWaitDuration, 2000, \ "Time in milliseconds that CMS thread waits for young GC") \ \ + develop(uintx, CMSCheckInterval, 1000, \ + "Interval in milliseconds that CMS thread checks if it " \ + "should start a collection cycle") \ + \ product(bool, CMSYield, true, \ "Yield between steps of concurrent mark & sweep") \ \ -- GitLab