Hi Florin,
Is it clear from the log if that happens?
Below is a shortened log with debug enabled for VCL and LDP.
Thanks
numactl --physcpubind=23 /home/<user>/scripts/start.sh
+ export LD_LIBRARY_PATH=/tmp/vpp_files/lib64/
+ LD_LIBRARY_PATH=/tmp/vpp_files/lib64/
+ export VCL_CONFIG=/tmp/vpp_files/vcl_startup.conf
+ VCL_CONFIG=/tmp/vpp_files/vcl_startup.conf
+ export VCL_DEBUG=2
+ VCL_DEBUG=2
+ export LDP_DEBUG=1
+ LDP_DEBUG=1
+ export LD_PRELOAD=/tmp/vpp_files/lib64/libvcl_ldpreload.so.26.10
+ LD_PRELOAD=/tmp/vpp_files/lib64/libvcl_ldpreload.so.26.10
+ exec java -cp ':/home/<user>/lib/*' MyApp
ldp<1121497>: configured LDP debug level (1) from env var LDP_DEBUG!
VCL<1121497>: configured VCL debug level (2) from VCL_DEBUG!
ldp<1121497>: fd 3: calling libc_close
allocated VCL heap = 0x7ff5973d63c0, size 268435456 (0x10000000)
VCL<1121497>: configured rx_fifo_size 400000 (0x61a80)
VCL<1121497>: configured tx_fifo_size 400000 (0x61a80)
VCL<1121497>: configured segment_size 1000000000 (0x3b9aca00)
VCL<1121497>: configured app_scope_global (1)
VCL<1121497>: configured app-socket-api (/var/run/vpp/app_ns_sockets/default)
VCL<1121497>: configured with mq with eventfd
VCL<1121497>: configured event_queue_size 100000 (0x186a0)
VCL<1121497>: completed parsing vppcom config!
ldp<1121497>: fd 3: calling libc_close
ldp<1121497>: calling libc_socket
ldp<1121497>: fd 4: calling libc_connect(): addr 0x7ffca456a532, len 110
ldp<1121497>: fd 7 vlsh -1, cmd 4
vppcom_app_init_common:1569: vcl<1121497:0>: app_name 'java-ldp-1121497',
my_client_index 1 (0x1)
ldp<1121497>: LDP initialization: done!
ldp_constructor:2874: LDP<1121497>: LDP constructor: done!
NOTE: Picked up JDK_JAVA_OPTIONS:
--add-opens=java.base/jdk.internal.misc=ALL-UNNAMED -Xms20G -Xmx20G
-XX:+UnlockExperimentalVMOptions -XX:+AlwaysPreTouch
-Djava.io.tmpdir=/home/<user>/var/services/run
Picked up JAVA_TOOL_OPTIONS: -Xlog:gc,gc+init::tags,time,uptime,level
-XX:+PrintFlagsFinal -Xms256m -Xmx1024m -Djava.net.preferIPv4Stack=true
-Duser.timezone=UTC -Duser.language=en -Duser.country=SE
ldp<1121497>: fd 9: calling libc_close
ldp<1121497>: fd 9: calling libc_close
ldp<1121497>: fd 9: calling libc_close
ldp<1121497>: fd 11 vlsh -1, cmd 1
ldp<1121497>: fd 9: calling libc_close
ldp<1121497>: fd 11: calling libc_close
[2026-07-09T21:53:42.613+0200][0.003s][info][gc,init] CardTable entry size: 512
[2026-07-09T21:53:42.613+0200][0.003s][info][gc ] Using Serial
[2026-07-09T21:53:47.308+0200][4.698s][info][gc,init] Version: 25.0.3+9-LTS
(release)
[2026-07-09T21:53:47.308+0200][4.698s][info][gc,init] CPUs: 32 total, 1
available
[2026-07-09T21:53:47.308+0200][4.698s][info][gc,init] Memory: 188G
[2026-07-09T21:53:47.308+0200][4.698s][info][gc,init] Large Page Support:
Disabled
[2026-07-09T21:53:47.308+0200][4.698s][info][gc,init] NUMA Support: Disabled
[2026-07-09T21:53:47.308+0200][4.698s][info][gc,init] Compressed Oops: Enabled
(Zero based)
[2026-07-09T21:53:47.308+0200][4.698s][info][gc,init] Heap Min Capacity: 20G
[2026-07-09T21:53:47.308+0200][4.698s][info][gc,init] Heap Initial Capacity: 20G
[2026-07-09T21:53:47.308+0200][4.698s][info][gc,init] Heap Max Capacity: 20G
[2026-07-09T21:53:47.308+0200][4.698s][info][gc,init] Pre-touch: Enabled
ldp<1121497>: fd 9: calling libc_close
[Global flags]
ccstr AOTCache =
{product} {default}
intx hashCode = 5
{experimental} {default}
ldp<1121497>: fd 0 vlsh -1, cmd 3
ldp<1121497>: fd 1 vlsh -1, cmd 3
ldp<1121497>: fd 2 vlsh -1, cmd 3
Error: Could not find or load main class MyApp
Caused by: java.lang.ClassNotFoundException: MyApp
ldp_destructor:2894: LDP<1121497>: LDP destructor: done!
#
# A fatal error has been detected by the Java Runtime Environment:
#
# SIGSEGV (0xb) at pc=0x00007ff5a758dbf6, pid=1121497, tid=1121505
#
# JRE version: OpenJDK Runtime Environment Temurin-25.0.3+9 (25.0.3+9) (build
25.0.3+9-LTS)
# Java VM: OpenJDK 64-Bit Server VM Temurin-25.0.3+9 (25.0.3+9-LTS, mixed mode,
sharing, tiered, compressed oops, compressed class ptrs, serial gc, linux-amd64)
# Problematic frame:
# C [libvppcom.so.26.10+0x19bf6] vcl_worker_cleanup+0x56
#
# Core dump will be written. Default location: core.1121497 (may not exist)
#
# An error report file with more information is saved as:
# /home/<user>/var/services/run/hs_err_pid1121497.log
#
# If you would like to submit a bug report, please visit:
# https://github.com/adoptium/adoptium-support/issues
#
________________________________
Från: [email protected] <[email protected]> för Florin Coras via
lists.fd.io <[email protected]>
Skickat: den 10 juli 2026 17:53
Till: [email protected] <[email protected]>
Ämne: Re: [vpp-dev] VCL/LDP segfault in vppcom_app_exit when exit handler is
run by an unexpected thread
Du får inte ofta e-post från [email protected]. Läs om varför
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Hi Jakob,
Would be interesting to understand why __vcl_worker_index is -1. Ideally when
constructor creates the app, it should initialize the first worker. Does that
initialize appropriately?
Regards,
Florin
On Jul 10, 2026, at 1:19 AM, Jakob Lövhall via lists.fd.io
<[email protected]> wrote:
Hi,
I tried running VPP with its LD_PRELOAD library on a Java app.
What I found was that it will segfault if the JVM encounters some kind of
issue, for example not finding the main class to run.
The segfault happens in vcl_worker_cleanup coming from vppcom_app_exit, it
looks like this is due to indexing issues when __vcl_worker_index is -1.
Here is a suggestion for patch to avoid it. Please consider it and add test
coverage for it.
```
diff --git a/src/vcl/vppcom.c b/src/vcl/vppcom.c
index 70d2674f9..873204945 100644
--- a/src/vcl/vppcom.c
+++ b/src/vcl/vppcom.c
@@ -1438,6 +1438,11 @@ vppcom_app_exit (void)
{
if (!pool_elts (vcm->workers))
return;
+
+ /* exiting thread never used vcl */
+ if (vcl_get_worker_index () == ~0)
+ return;
+
vcl_worker_cleanup (vcl_worker_get_current (), 1 /* notify vpp */ );
vcl_set_worker_index (~0);
vcl_elog_stop (vcm);
```
This is what the segfault backtrace looks like in gdb
```
Error: Could not find or load main class MainClass
Caused by: java.lang.ClassNotFoundException: MainClass
[Thread 0x7fff4ffff6c0 (LWP 1119246) exited]
[Thread 0x7fff641f96c0 (LWP 1119243) exited]
[Thread 0x7fff642fa6c0 (LWP 1119242) exited]
[Thread 0x7fff66b9d6c0 (LWP 1119240) exited]
Thread 11 "VM Thread" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fff4fefe6c0 (LWP 1119247)]
vcl_worker_cleanup (wrk=wrk@entry=0x853fe7bd0140, notify_vpp=notify_vpp@entry=1
'\001') at vpp/src/vcl/vcl_private.c:123
warning: 123 vpp/src/vcl/vcl_private.c: No such file or directory
(gdb) bt
#0 vcl_worker_cleanup (wrk=wrk@entry=0x853fe7bd0140,
notify_vpp=notify_vpp@entry=1 '\001') at vpp/src/vcl/vcl_private.c:123
#1 0x00007ffff7d6ffb6 in vppcom_app_exit () at vpp/src/vcl/vppcom.c:1441
#2 0x00007ffff7dec231 in __cxa_finalize () from
/lib64/libc.so<http://libc.so/>.6
#3 0x00007ffff7d6e1b7 in __do_global_dtors_aux () from
/tmp/vpp_files/lib64/libvppcom.so<http://libvppcom.so/>.26.10
#4 0x00007ffff7fc1a50 in ?? ()
#5 0x00007ffff7fc90e2 in _dl_call_fini (closure_map=0x7fff4fefd5a0,
closure_map@entry=0x7ffff7fc1a50) at dl-call_fini.c:43
#6 0x00007ffff7fcd370 in _dl_fini () at dl-fini.c:120
#7 0x00007ffff7dec7b1 in __run_exit_handlers () from
/lib64/libc.so<http://libc.so/>.6
#8 0x00007ffff7dec880 in exit () from /lib64/libc.so<http://libc.so/>.6
#9 0x00007fffa9880c79 in os::exit(int) () from
/home/<user>/.sdkman/candidates/java/25.0.3-tem/lib/server/libjvm.so<http://libjvm.so/>
#10 0x00007fffa942104c in vm_direct_exit(int) () from
/home/<user>/.sdkman/candidates/java/25.0.3-tem/lib/server/libjvm.so<http://libjvm.so/>
#11 0x00007fffa9c96a67 in VM_Operation::evaluate() () from
/home/<user>/.sdkman/candidates/java/25.0.3-tem/lib/server/libjvm.so<http://libjvm.so/>
#12 0x00007fffa9c9a0a2 in VMThread::evaluate_operation(VM_Operation*) () from
/home/<user>/.sdkman/candidates/java/25.0.3-tem/lib/server/libjvm.so<http://libjvm.so/>
#13 0x00007fffa9c9acd7 in VMThread::inner_execute(VM_Operation*) () from
/home/<user>/.sdkman/candidates/java/25.0.3-tem/lib/server/libjvm.so<http://libjvm.so/>
#14 0x00007fffa9c9af97 in VMThread::run() () from
/home/<user>/.sdkman/candidates/java/25.0.3-tem/lib/server/libjvm.so<http://libjvm.so/>
#15 0x00007fffa9bf842f in Thread::call_run() () from
/home/<user>/.sdkman/candidates/java/25.0.3-tem/lib/server/libjvm.so<http://libjvm.so/>
#16 0x00007fffa9875b16 in thread_native_entry(Thread*) () from
/home/<user>/.sdkman/candidates/java/25.0.3-tem/lib/server/libjvm.so<http://libjvm.so/>
#17 0x00007ffff7e3ea7f in start_thread () from /lib64/libc.so<http://libc.so/>.6
#18 0x00007ffff7eaf4fc in clone3 () from /lib64/libc.so<http://libc.so/>.6
```
I created a minimal reproducer with Java. Which was just HelloWorld and then
misspell the main class such that it cannot be found, but I see that I am not
allowed to attach tar.gz files. The reproducer stays with me for now. Hopefully
you can reproduce it on your own.
Thanks,
Jakob
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