Getting a stack dump when closing RocksDB at the end of the service

[jnioche]

#
# A fatal error has been detected by the Java Runtime Environment:
#
#  SIGSEGV (0xb) at pc=0x00007fa253424f47, pid=568380, tid=0x00007fa1ff7fa700
#
# JRE version: OpenJDK Runtime Environment (8.0_292-b10) (build 1.8.0_292-8u292-b10-0ubuntu1~20.04-b10)
# Java VM: OpenJDK 64-Bit Server VM (25.292-b10 mixed mode linux-amd64 compressed oops)
# Problematic frame:
# C  [librocksdbjni2589559341903054454.so+0x326f47]  rocksdb::DBImpl::NewIterator(rocksdb::ReadOptions const&, rocksdb::ColumnFamilyHandle*)+0x47
#
# Failed to write core dump. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimited" before starting Java again
#
# An error report file with more information is saved as:
# /users/jnioche/url-frontier/service/hs_err_pid568380.log
[thread 140333751965440 also had an error]
[thread 140333838980864 also had an error]
[thread 140333883029248 also had an error]
[thread 140335108507392 also had an error]
[thread 140333745649408 also had an error]
[thread 140333750912768 also had an error]
[thread 140333754070784 also had an error]
#
# If you would like to submit a bug report, please visit:
#   http://bugreport.java.com/bugreport/crash.jsp
#

[jnioche]

This is likely to be due to closing the rocksb instance while some operations are still running. Checking whether closing has been requested should reduce the frequency of the problem.

[aecio]

I also ran into a similar error in ACHE crawler, which I reported here: facebook/rocksdb#5234. But in this case, URLFrontier seems to fail when a new iterator is created after the DB is closed.

[jnioche]

thanks @aecio. Did not know about ACHE crawler, will have a look. The commit from Friday should help with the issue, will try to see if it still breaks next week.