On Fri, 24 Nov 2023 06:57:33 GMT, Jaikiran Pai <j...@openjdk.org> wrote:
>> Can I please get a review of this change which proposes to fix the issue >> noted in https://bugs.openjdk.org/browse/JDK-8320687? >> >> As noted in the issue, the >> `sun.jvmstat.monitor.MonitoredHost.getMonitoredHost()` uses a shared >> instance of `java.util.ServiceLoader` to load `MonitoredHostService` >> services. The `ServiceLoader` class javadoc explicitly notes that it isn't >> thread safe. The issue at hand is caused to due using an instance of >> `ServiceLoader` concurrently by multiple threads. >> >> The fix proposes to guard the usage of the shared `ServiceLoader` instance >> through the `monitoredHosts` object monitor. We already use that monitor >> when dealing with the internal cache which is populated after loading the >> relevant `MonitoredHostService`(s). >> >> A new jtreg test has been introduced which always reproduces the issue >> without the source changes and passes with this fix. >> >> tier1, tier2, tier3 and svc_tools tests have been run with this change and >> all passed. > > Jaikiran Pai has updated the pull request incrementally with two additional > commits since the last revision: > > - Alan's review suggestion - rename GetMonitoredHost to > ConcurrentGetMonitoredHost > - fix code comment Hello Kevin, > Do we really need both synchronized(monitoredHosts) blocks -- is the first > one needed, now at lines 159 -164 ? If we don't, then you might not feel the need to create the getCachedMonitoredHost() method which separates the locking from the access you want to protect. That's a good point. I have taken your input and updated the PR to simplify the synchronized block. The test continues to pass locally (I'll re-run tier testing and svc_tools later today). ------------- PR Comment: https://git.openjdk.org/jdk/pull/16805#issuecomment-1825536913
