Hi, me again ;)
I think I've found the root cause of this. There's a tiny race in the
ZGC allocation path, which can lead to pre-mature OOME being thrown.
It's not trivial to fix, so I suggest you go ahead with your original
patch (Looks good btw), and I'll file a separate bug to fix the ZGC
issue (and update this test to run with ZGC again).
cheers,
Per
On 12/13/2018 12:21 PM, Per Liden wrote:
Hi again,
I ran this test some more and managed to get an OOME even with a 768M
heap. I'm getting a bit suspicious that something else is wrong here.
Let me dig into this some more and see if I can understand what the real
issue is.
cheers,
Per
On 12/13/2018 10:31 AM, Per Liden wrote:
Hi JC,
What's the reason to exclude ZGC from this test to begin with? From
what I can tell, it's because the test is using a slightly too small
heap, or are there some other reason? I ran it a few times using
various heap sizes and the test passes with ZGC when using anything
above 612M. So if we instead just dump the heap size a bit, then we
get test coverage with ZGC too. I picked 768M here to have some
headroom in case the exact limit is run-to-run dependent.
diff --git
a/test/hotspot/jtreg/serviceability/jvmti/HeapMonitor/MyPackage/HeapMonitorThreadTest.java
b/test/hotspot/jtreg/serviceability/jvmti/HeapMonitor/MyPackage/HeapMonitorThreadTest.java
---
a/test/hotspot/jtreg/serviceability/jvmti/HeapMonitor/MyPackage/HeapMonitorThreadTest.java
+++
b/test/hotspot/jtreg/serviceability/jvmti/HeapMonitor/MyPackage/HeapMonitorThreadTest.java
@@ -29,8 +29,7 @@
* @build Frame HeapMonitor ThreadInformation
* @summary Verifies the JVMTI Heap Monitor Thread information sanity.
* @compile HeapMonitorThreadTest.java
- * @run main/othervm/native -Xmx512m -agentlib:HeapMonitorTest
MyPackage.HeapMonitorThreadTest
- * @requires !vm.gc.Z
+ * @run main/othervm/native -Xmx768m -agentlib:HeapMonitorTest
MyPackage.HeapMonitorThreadTest
*/
import java.util.List;
cheers,
Per
On 12/13/2018 05:44 AM, JC Beyler wrote:
Hi all,
When working on another webrev, I saw this problem:
Webrev: http://cr.openjdk.java.net/~jcbeyler/8215329/webrev.00/
Bug: https://bugs.openjdk.java.net/browse/JDK-8215329
(Basically, from what I understood from an email from Per Liden:
- @requires !vm.gc.Z -> ZGC is built in the JDK
- @requires vm.gc != "Z" -> ZGC is being used for the runtime
)
Thanks,
Jc
