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<p><font face="monospace">FYI<br>
</font></p>
<p><font face="monospace">I am working on a related problem where
some hidden classes are incorrectly excluded. They have names
that look like:</font></p>
<p><font face="monospace">io/vertx/core/impl/VertxImpl$$InjectedInvoker+0x8000000c6<br>
java/util/logging/Level$KnownLevel$$InjectedInvoker+0x800000028<br>
</font></p>
<p><font face="monospace">or<br>
<br>
org/openjdk/bench/java/lang/StringConcat$$StringConcat+0x800000022<br>
</font></p>
<p><font face="monospace">The root cause is different than what
Ashutosh reported -- we have resolved CP entries that
transitively point to Method* of hidden classes. So far this
problem is not reproducible with existing test cases in the
premain branch. I am testing a fix now.</font></p>
<p><font face="monospace">Thanks</font></p>
<p><font face="monospace">- Ioi<br>
</font></p>
<p><font face="monospace"><br>
</font></p>
<div class="moz-cite-prefix"><font face="monospace">On 6/27/24 8:14
PM, Ashutosh Mehra wrote:<br>
</font></div>
<blockquote type="cite" cite="mid:CAKt0pyR698qrOewyzmJmZHrfuzFfu=BwUMWtdO1XHKtHOPwzYw@mail.gmail.com">
<div dir="ltr"><font face="monospace">I encountered a crash when
dumping the cds map with 1-step workflow.</font>
<div><font face="monospace">The crash happens in the forked JVM
during the assembly phase of the training run.</font></div>
<div><font face="monospace">To recreate the crash, execute the
training run with -Xlog:cds+map=trace:file=cds.map:none:filesize=0
option.</font></div>
<div><font face="monospace"><br>
</font></div>
<div><font face="monospace">#<br>
# A fatal error has been detected by the Java Runtime
Environment:<br>
#<br>
# SIGSEGV (0xb) at pc=0x00007f4e8a209cb6, pid=152509,
tid=152510<br>
#<br>
# JRE version: OpenJDK Runtime Environment (23.0) (slowdebug
build 23-internal-adhoc.asmehra.leyden)<br>
# Java VM: OpenJDK 64-Bit Server VM (slowdebug
23-internal-adhoc.asmehra.leyden, mixed mode, sharing,
tiered, compressed oops, compressed class ptrs, g1 gc,
linux-amd64)<br>
# Problematic frame:<br>
# V [libjvm.so+0x409cb6] Klass::is_instance_klass()
const+0x10<br>
#<br>
# Core dump will be written. Default location:
/home/asmehra/data/ashu-mehra/leyden/test/hotspot/jtreg/premain/quarkus-getting-started/core.152509<br>
#<br>
# An error report file with more information is saved as:<br>
#
/home/asmehra/data/ashu-mehra/leyden/test/hotspot/jtreg/premain/quarkus-getting-started/hs_err_pid152509.log<br>
#<br>
# If you would like to submit a bug report, please visit:<br>
# <a href="https://bugreport.java.com/bugreport/crash.jsp" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">https://bugreport.java.com/bugreport/crash.jsp</a><br>
#<br>
[75.250s][error ][cds] Child process finished; status = 134<br>
<br>
</font></div>
<div><font face="monospace">Backtrace for the crashing thread:</font></div>
<div><font face="monospace"><br>
</font></div>
<div><font face="monospace">#11 0x00007f4e8a209cb6 in
Klass::is_instance_klass (this=0x0) at
/home/asmehra/data/ashu-mehra/leyden/src/hotspot/share/oops/klass.hpp:683<br>
#12 0x00007f4e8afa8894 in Klass::external_name (this=0x0) at
/home/asmehra/data/ashu-mehra/leyden/src/hotspot/share/oops/klass.cpp:905<br>
#13 0x00007f4e8b126447 in Method::print_external_name
(os=0x7f4e89dfd130, klass=0x0, method_name=0x8011e8588,
signature=0x8011ab858) at
/home/asmehra/data/ashu-mehra/leyden/src/hotspot/share/oops/method.cpp:228<br>
#14 0x00007f4e8b1263b6 in Method::external_name (klass=0x0,
method_name=0x8011e8588, signature=0x8011ab858) at
/home/asmehra/data/ashu-mehra/leyden/src/hotspot/share/oops/method.cpp:222<br>
#15 0x00007f4e8b1262e1 in Method::external_name
(this=0x800fd1920) at
/home/asmehra/data/ashu-mehra/leyden/src/hotspot/share/oops/method.cpp:213<br>
#16 0x00007f4e8a492b0d in
ArchiveBuilder::CDSMapLogger::log_method (m=0x800fd1920,
runtime_dest=0x801039cd8 "", type_name=0x7f4e8b7d40fc
"Method", bytes=128, current=0x7f4e8401d900)<br>
at
/home/asmehra/data/ashu-mehra/leyden/src/hotspot/share/cds/archiveBuilder.cpp:1194<br>
#17 0x00007f4e8a492d66 in
ArchiveBuilder::CDSMapLogger::log_metaspace_objects
(region=0x7f4e89dfe740, src_objs=0x7f4e89dfe860) at
/home/asmehra/data/ashu-mehra/leyden/src/hotspot/share/cds/archiveBuilder.cpp:1228<br>
#18 0x00007f4e8a492a2b in
ArchiveBuilder::CDSMapLogger::log_metaspace_region
(name=0x7f4e8b7d8af0 "rw region", region=0x7f4e89dfe740,
src_objs=0x7f4e89dfe860) at
/home/asmehra/data/ashu-mehra/leyden/src/hotspot/share/cds/archiveBuilder.cpp:1182<br>
#19 0x00007f4e8a4940f4 in ArchiveBuilder::CDSMapLogger::log
(builder=0x7f4e89dfe630, mapinfo=0x7f4e85017bb0,
heap_info=0x7f4e89dfd4f0, bitmap=0x7f4e857bf850
"\t\222\004I\222$\t\210\210\210\001\b\200",
bitmap_size_in_bytes=655824)<br>
at
/home/asmehra/data/ashu-mehra/leyden/src/hotspot/share/cds/archiveBuilder.cpp:1502<br>
#20 0x00007f4e8a48f2a5 in ArchiveBuilder::write_archive
(this=0x7f4e89dfe630, mapinfo=0x7f4e85017bb0,
heap_info=0x7f4e89dfd4f0) at
/home/asmehra/data/ashu-mehra/leyden/src/hotspot/share/cds/archiveBuilder.cpp:1560<br>
#21 0x00007f4e8b11d249 in
MetaspaceShared::write_static_archive
(builder=0x7f4e89dfe630, mapinfo=0x7f4e85017bb0,
heap_info=0x7f4e89dfd4f0) at
/home/asmehra/data/ashu-mehra/leyden/src/hotspot/share/cds/metaspaceShared.cpp:988<br>
#22 0x00007f4e8b11d1ac in
MetaspaceShared::preload_and_dump_impl (builder=...,
__the_thread__=0x7f4e8401d900) at
/home/asmehra/data/ashu-mehra/leyden/src/hotspot/share/cds/metaspaceShared.cpp:976<br>
#23 0x00007f4e8b11c5fd in MetaspaceShared::preload_and_dump
() at
/home/asmehra/data/ashu-mehra/leyden/src/hotspot/share/cds/metaspaceShared.cpp:767<br>
#24 0x00007f4e8b53bca2 in Threads::create_vm
(args=0x7f4e89dfedd0, canTryAgain=0x7f4e89dfecd3) at
/home/asmehra/data/ashu-mehra/leyden/src/hotspot/share/runtime/threads.cpp:900<br>
#25 0x00007f4e8ada2821 in JNI_CreateJavaVM_inner
(vm=0x7f4e89dfee20, penv=0x7f4e89dfee28,
args=0x7f4e89dfedd0) at
/home/asmehra/data/ashu-mehra/leyden/src/hotspot/share/prims/jni.cpp:3581<br>
#26 0x00007f4e8ada2c81 in JNI_CreateJavaVM
(vm=0x7f4e89dfee20, penv=0x7f4e89dfee28,
args=0x7f4e89dfedd0) at
/home/asmehra/data/ashu-mehra/leyden/src/hotspot/share/prims/jni.cpp:3672<br>
#27 0x00007f4e8ce0f84f in InitializeJVM (pvm=0x7f4e89dfee20,
penv=0x7f4e89dfee28, ifn=0x7f4e89dfee70) at
/home/asmehra/data/ashu-mehra/leyden/src/java.base/share/native/libjli/java.c:1550</font></div>
<div><font face="monospace"><br>
</font></div>
<div><font face="monospace">Checking up the CDS map generated
for the cds preimage shows some methods for which their
InstanceKlass is null. </font></div>
<div><font face="monospace">This results in the crash seen above
when such methods are printed as part of the CDS map file
during the assembly phase.</font></div>
<div><font face="monospace"><br>
</font></div>
<div><font face="monospace">These methods are of the form:</font></div>
<div><font face="monospace"><br>
</font></div>
<div><font face="monospace">java.lang.Object
java.lang.invoke.LambdaForm$MH/0x800000090.invoke(java.lang.Object,
java.lang.Object)<br>
</font></div>
<div><font face="monospace"><br>
</font></div>
<div><font face="monospace">Interestingly -Xlog:cds=info shows
such classes are skipped when generating the preimage as
they are hidden classes:</font></div>
<div><font face="monospace"><br>
</font></div>
<div><font face="monospace">Skipping
java/lang/invoke/LambdaForm$MH+0x800000090: Hidden class<br>
</font></div>
<div><font face="monospace"><br>
</font></div>
<div><font face="monospace">In the CDS map file for the preimage
I also noticed that such methods are only referenced through
MethodTrainingData -> _final_profile -> _method.<br>
So it looks like although we excluded such classes from the
CDS archive, we don't exclude their training data.<br>
There is code for cleaning up the training data [0] , but it
doesn't remove the training data for classes that have been
excluded, unless I misunderstood the code.<br>
Not sure if it is intentional or a bug.<br>
</font></div>
<div><font face="monospace">If we do need to keep the training
data for such methods, then we would need to handle the case
of null InstanceKlass in the CDSMapLogger to avoid crashing.</font></div>
<div><font face="monospace"><br>
</font></div>
<div><font face="monospace">[0] <a href="https://github.com/openjdk/leyden/blob/8716f47ef49c829e2384474577ff468a732b9c66/src/hotspot/share/oops/trainingData.cpp#L573" moz-do-not-send="true" class="moz-txt-link-freetext">https://github.com/openjdk/leyden/blob/8716f47ef49c829e2384474577ff468a732b9c66/src/hotspot/share/oops/trainingData.cpp#L573</a><br>
</font></div>
<div><font face="monospace"><br>
</font></div>
<div><font face="monospace">Thanks,<br>
</font>
<div>
<div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature">
<div dir="ltr"><font face="monospace">- Ashutosh Mehra</font></div>
</div>
</div>
</div>
</div>
</blockquote>
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