Crash when dumping cds map file

ioi.lam at oracle.com ioi.lam at oracle.com
Tue Jul 2 05:27:42 UTC 2024 

I filed a bug for this issue and pushed a fixed to the "premain" branch

https://bugs.openjdk.org/browse/JDK-8335492 "Some hidden classes are not 
archived for ArchiveInvokeDynamic"

Thanks

- Ioi


On 6/28/24 7:21 PM, ioi.lam at oracle.com wrote:
>
> FYI
>
> I am working on a related problem where some hidden classes are 
> incorrectly excluded. They have names that look like:
>
> io/vertx/core/impl/VertxImpl$$InjectedInvoker+0x8000000c6
> java/util/logging/Level$KnownLevel$$InjectedInvoker+0x800000028
>
> or
>
> org/openjdk/bench/java/lang/StringConcat$$StringConcat+0x800000022
>
> 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.
>
> Thanks
>
> - Ioi
>
>
> On 6/27/24 8:14 PM, Ashutosh Mehra wrote:
>> I encountered a crash when dumping the cds map with 1-step workflow.
>> The crash happens in the forked JVM during the assembly phase of the 
>> training run.
>> To recreate the crash, execute the training run 
>> with -Xlog:cds+map=trace:file=cds.map:none:filesize=0 option.
>>
>> #
>> # A fatal error has been detected by the Java Runtime Environment:
>> #
>> #  SIGSEGV (0xb) at pc=0x00007f4e8a209cb6, pid=152509, tid=152510
>> #
>> # JRE version: OpenJDK Runtime Environment (23.0) (slowdebug build 
>> 23-internal-adhoc.asmehra.leyden)
>> # 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)
>> # Problematic frame:
>> # V  [libjvm.so+0x409cb6]  Klass::is_instance_klass() const+0x10
>> #
>> # Core dump will be written. Default location: 
>> /home/asmehra/data/ashu-mehra/leyden/test/hotspot/jtreg/premain/quarkus-getting-started/core.152509
>> #
>> # An error report file with more information is saved as:
>> # 
>> /home/asmehra/data/ashu-mehra/leyden/test/hotspot/jtreg/premain/quarkus-getting-started/hs_err_pid152509.log
>> #
>> # If you would like to submit a bug report, please visit:
>> # https://bugreport.java.com/bugreport/crash.jsp
>> #
>> [75.250s][error  ][cds] Child process finished; status = 134
>>
>> Backtrace for the crashing thread:
>>
>> #11 0x00007f4e8a209cb6 in Klass::is_instance_klass (this=0x0) at 
>> /home/asmehra/data/ashu-mehra/leyden/src/hotspot/share/oops/klass.hpp:683
>> #12 0x00007f4e8afa8894 in Klass::external_name (this=0x0) at 
>> /home/asmehra/data/ashu-mehra/leyden/src/hotspot/share/oops/klass.cpp:905
>> #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
>> #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
>> #15 0x00007f4e8b1262e1 in Method::external_name (this=0x800fd1920) at 
>> /home/asmehra/data/ashu-mehra/leyden/src/hotspot/share/oops/method.cpp:213
>> #16 0x00007f4e8a492b0d in ArchiveBuilder::CDSMapLogger::log_method 
>> (m=0x800fd1920, runtime_dest=0x801039cd8 "", type_name=0x7f4e8b7d40fc 
>> "Method", bytes=128, current=0x7f4e8401d900)
>>     at 
>> /home/asmehra/data/ashu-mehra/leyden/src/hotspot/share/cds/archiveBuilder.cpp:1194
>> #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
>> #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
>> #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)
>>     at 
>> /home/asmehra/data/ashu-mehra/leyden/src/hotspot/share/cds/archiveBuilder.cpp:1502
>> #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
>> #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
>> #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
>> #23 0x00007f4e8b11c5fd in MetaspaceShared::preload_and_dump () at 
>> /home/asmehra/data/ashu-mehra/leyden/src/hotspot/share/cds/metaspaceShared.cpp:767
>> #24 0x00007f4e8b53bca2 in Threads::create_vm (args=0x7f4e89dfedd0, 
>> canTryAgain=0x7f4e89dfecd3) at 
>> /home/asmehra/data/ashu-mehra/leyden/src/hotspot/share/runtime/threads.cpp:900
>> #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
>> #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
>> #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
>>
>> Checking up the CDS map generated for the cds preimage shows some 
>> methods for which their InstanceKlass is null.
>> This results in the crash seen above when such methods are printed as 
>> part of the CDS map file during the assembly phase.
>>
>> These methods are of the form:
>>
>> java.lang.Object 
>> java.lang.invoke.LambdaForm$MH/0x800000090.invoke(java.lang.Object, 
>> java.lang.Object)
>>
>> Interestingly -Xlog:cds=info shows such classes are skipped when 
>> generating the preimage as they are hidden classes:
>>
>> Skipping java/lang/invoke/LambdaForm$MH+0x800000090: Hidden class
>>
>> In the CDS map file for the preimage I also noticed that such methods 
>> are only referenced through MethodTrainingData -> _final_profile -> 
>> _method.
>> So it looks like although we excluded such classes from the CDS 
>> archive, we don't exclude their training data.
>> 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.
>> Not sure if it is intentional or a bug.
>> 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.
>>
>> [0] 
>> https://github.com/openjdk/leyden/blob/8716f47ef49c829e2384474577ff468a732b9c66/src/hotspot/share/oops/trainingData.cpp#L573
>>
>> Thanks,
>> - Ashutosh Mehra
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