On Wed, 19 Oct 2022 19:42:31 GMT, Chris Plummer <cjplum...@openjdk.org> wrote:
>> Found this when working on JOL support >> ([CODETOOLS-7903364](https://bugs.openjdk.org/browse/CODETOOLS-7903364)). If >> you try to attach to VM running with -XX:ObjectAlignmentInBytes=32, then SA >> would fail with: >> >> >> Caused by: java.lang.RuntimeException: Object alignment 32 not yet supported >> at jdk.hotspot.agent/sun.jvm.hotspot.runtime.VM.<init>(VM.java:510) >> at jdk.hotspot.agent/sun.jvm.hotspot.runtime.VM.initialize(VM.java:544) >> at >> jdk.hotspot.agent/sun.jvm.hotspot.HotSpotAgent.setupVM(HotSpotAgent.java:444) >> >> >> This code was added by >> [JDK-6916623](https://bugs.openjdk.org/browse/JDK-6916623), but I don't see >> a reason why it should only handle 8 and 16 byte alignment. >> >> Additional testing: >> - [x] New regression test >> - [x] Linux x86_64 fastdebug `serviceability/sa` >> - default >> - with `-XX:ObjectAlignmentInBytes=16` >> - with `-XX:ObjectAlignmentInBytes=32` >> - with `-XX:ObjectAlignmentInBytes=64` >> - with `-XX:ObjectAlignmentInBytes=128` >> - with `-XX:ObjectAlignmentInBytes=256` > > src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/runtime/VM.java line 505: > >> 503: >> 504: minObjAlignmentInBytes = getObjectAlignmentInBytes(); >> 505: if (minObjAlignmentInBytes < 8 || minObjAlignmentInBytes > 256 || > > Is it necessary to restrict it to the 8 -> 256 range. I know this is the > current hotspot restriction, but if hotspot decided to allow a larger range, > is there any reason SA wouldn't still work? I don't think there is anything specific in SA that prohibits it to follow what Hotspot is capable of. Are you proposing to drop the range check altogether? I can do that. ------------- PR: https://git.openjdk.org/jdk/pull/10762
