JDK-6949307 : G1: raise a vm error, do not core dump, if target pause time and target interval are inconsistent
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: gc
  • Affected Version: hs18
  • Priority: P4
  • Status: Closed
  • Resolution: Fixed
  • OS: generic
  • CPU: generic
  • Submitted: 2010-05-03
  • Updated: 2013-09-18
  • Resolved: 2011-03-08
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JDK 6 JDK 7 Other
6u21pFixed 7Fixed hs19Fixed
Description
Currently, the default pause time interval is 500ms. If a user sets a pause time target -XX:MaxGCPauseMillis=P, where P >= 500ms, without setting the interval explicitly with -XX:GCPauseIntervalMillis=T, G1 core dumps as we hit a guarantee that says that the pause time target should be less than the interval:

#
# A fatal error has been detected by the Java Runtime Environment:
#
#  Internal Error (g1CollectorPolicy.cpp:265), pid=7197, tid=2
#  Error: guarantee(max_gc_time < time_slice,"Max GC time should not be greater than the time slice")
#

There are two changes we should make:

a) raise a vm error, not a guarantee failure / core dump
b) deal quietly with the case where the specified pause time target is >= the default interval
Comments
EVALUATION http://hg.openjdk.java.net/jdk7/hotspot-gc/hotspot/rev/79107c3a6bd5
23-06-2010
SUGGESTED FIX The policy change is going to be the following: we are not going to give a default time interval. If the time interval is not explicitly set by the user, we are going to set it to pause_time_goal + 1 to basically give G1 maximum flexibility in terms of scheduling pauses. A user will, of course, be able to override that if they wish.
04-05-2010
EVALUATION See Description.
03-05-2010