Occasional segmentation fault when running market tests

[devos50]

The market tests segfault sometimes:

Test trading between two persons, with a matchmaker ... /home/jenkins/workspace/GH_Tribler_PR_tests_linux/gumby/scripts/wrap_in_temp_home.sh: line 34: 44161 Segmentation fault      (core dumped) $*
+ FAILURE=139

After analysing the core dump file with gdb, I got the following stack trace:

GNU gdb (Debian 7.12-6+b1) 7.12.0.20161007-git
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Reading symbols from /usr/bin/python2.7...Reading symbols from /usr/lib/debug/.build-id/20/6b80329daae2f6c7d03485fab33497a34c59bd.debug...done.
done.

warning: core file may not match specified executable file.
[New LWP 45471]
[New LWP 45468]
[New LWP 44161]
[New LWP 45246]
[New LWP 45474]
[New LWP 45472]
[New LWP 45473]
[New LWP 45476]
[New LWP 45469]
[New LWP 44249]
[New LWP 45477]
[New LWP 45475]
[New LWP 45470]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Core was generated by `/usr/bin/python /usr/bin/nosetests -v --with-xcoverage --xunit-file=/home/jenki'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  _pysqlite_query_execute () at ./Modules/_sqlite/cursor.c:678
678	./Modules/_sqlite/cursor.c: No such file or directory.
[Current thread is 1 (Thread 0x7f390dc5f700 (LWP 45471))]
(gdb) py-bt
Traceback (most recent call first):
  (frame information optimized out)
  (frame information optimized out)
  File "/home/jenkins/workspace/GH_Tribler_PR_tests_linux/tribler/Tribler/pyipv8/ipv8/attestation/trustchain/database.py", line 49, in _get
    db_result = list(self.execute(self.get_sql_header() + query, params, fetch_all=False))
  File "/home/jenkins/workspace/GH_Tribler_PR_tests_linux/tribler/Tribler/pyipv8/ipv8/attestation/trustchain/database.py", line 101, in get_block_before
    (block.sequence_number, buffer(block.public_key)))
  (frame information optimized out)
  File "/home/jenkins/workspace/GH_Tribler_PR_tests_linux/tribler/Tribler/pyipv8/ipv8/attestation/trustchain/community.py", line 210, in validate_persist_block
    validation = block.validate(self.persistence)
  (frame information optimized out)
  (frame information optimized out)
  File "/home/jenkins/workspace/GH_Tribler_PR_tests_linux/tribler/Tribler/community/market/community.py", line 506, in received_half_block_pair_broadcast
    super(MarketCommunity, self).received_half_block_pair_broadcast(source_address, data)
  (frame information optimized out)
  (frame information optimized out)
  (frame information optimized out)
  (frame information optimized out)
  (frame information optimized out)
  (frame information optimized out)
  (frame information optimized out)
  (frame information optimized out)
  File "/usr/lib/python2.7/threading.py", line 754, in run
    self.__target(*self.__args, **self.__kwargs)
  File "/usr/lib/python2.7/threading.py", line 801, in __bootstrap_inner
    self.run()
  (frame information optimized out)

It seems that there's an issue when handling incoming blocks on the threadpool.

[devos50]

I'm able to reproduce this issue on bbq and it is caused by messages that come in after the market community has been unloaded. This means that the timeout for the deliver_messages call is too low, however, I suspect that signature validation of TradeChain blocks take a considerable amount of time.

[devos50]

It seems to be non-trivial to disable block validation for the tests since the code is quite deep in the validator. Increasing the timeout for the deliver_messages in the market tests seems to work.