User_var_log_event::User_var_log_event(const char*, uint, const Format_description_log_event*): Assertion `(bytes_read == (data_written - ((old_pre_checksum_fd || (description_event->checksum_alg == BINLOG_CHECKSUM_ALG_OFF)) ? 0 : 4))) || ((bytes_read == (data_written -1 - (old_pre_checksum_fd || (description_event->checksum_alg == BINLOG_CHECKSUM_ALG_OFF)) ? 0 : 4)))' failed.

[Roel Van de Paar]

1) This looks like a new regression. Never seen before.
2) The issue is currently only reproducible through a set of scripts prepared & reduced by reducer.sh. Not sure why I cannot get it to replay at the mysql client (yet). Here is the SQL;

# mysqld options required for replay: --log-bin
USE test;
create temporary TABLE t0(i int);
set @a=0,@b=0;
INSERT INTO t0 VALUES(@b);
show binlog events;

3) Here is how to use this testcase;

The attached tarball (1512639429_bug_bundle.tar.gz) gives the testcase as an exact match of our system, including some handy utilities

$ vi 1512639429_mybase # STEP1: Update the base path in this file (usually the only change required!). If you use a non-binary distribution, please update SOURCE_DIR location also
$ ./1512639429_init # STEP2: Initializes the data dir
$ ./1512639429_start # STEP3: Starts mysqld
$ ./1512639429_cl # STEP4: To check mysqld is up
$ ./1512639429_run_pquery # STEP5: Run the testcase with the pquery binary
$ ./1512639429_run # STEP5 ALTERNATIVE: Run the testcase with the mysql CLI (also reproduces the issue on my system)
$ vi /dev/shm/1512639429/error.log.out # STEP6: Verify the error log
$ ./1512639429_gdb # OPTIONAL: Brings you to a gdb prompt with gdb attached to the used mysqld and attached to the generated core
$ ./1512639429_parse_core # OPTIONAL: Creates 1512639429_STD.gdb and 1512639429_FULL.gdb; standard and full variables gdb stack traces

[Roel Van de Paar (roel11)]

2017-12-08 05:58:02 12735 [Note] /sda/PS021217-percona-server-5.6.38-82.3-linux-x86_64-debug/bin/mysqld: ready for connections.
Version: '5.6.38-82.3-debug-log' socket: '/dev/shm/1512639429/socket.sock' port: 35021 MySQL Community Server (GPL)
mysqld: /git/PS-5.6-trunk_dbg/sql/log_event.cc:7852: User_var_log_event::User_var_log_event(const char*, uint, const Format_description_log_event*): Assertion `(bytes_read == (data_written - ((old_pre_checksum_fd || (description_event->checksum_alg == BINLOG_CHECKSUM_ALG_OFF)) ? 0 : 4))) || ((bytes_read == (data_written -1 - (old_pre_checksum_fd || (description_event->checksum_alg == BINLOG_CHECKSUM_ALG_OFF)) ? 0 : 4)))' failed.
18:58:03 UTC - mysqld got signal 6 ;

Core was generated by `/sda/PS021217-percona-server-5.6.38-82.3-linux-x86_64-debug/bin/mysqld --no-def'.
Program terminated with signal 6, Aborted.
#0 0x00007ff36946c9b1 in __pthread_kill (threadid=<optimized out>, signo=6) at ../nptl/sysdeps/unix/sysv/linux/pthread_kill.c:61
61 val = INTERNAL_SYSCALL (tgkill, err, 3, THREAD_GETMEM (THREAD_SELF, pid),
(gdb) bt
#0 0x00007ff36946c9b1 in __pthread_kill (threadid=<optimized out>, signo=6) at ../nptl/sysdeps/unix/sysv/linux/pthread_kill.c:61
#1 0x0000000000aca231 in my_write_core (sig=6) at /git/PS-5.6-trunk_dbg/mysys/stacktrace.c:424
#2 0x000000000073a92d in handle_fatal_signal (sig=6) at /git/PS-5.6-trunk_dbg/sql/signal_handler.cc:236
#3 <signal handler called>
#4 0x00007ff3677841f7 in __GI_raise (sig=sig@entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:56
#5 0x00007ff3677858e8 in __GI_abort () at abort.c:90
#6 0x00007ff36777d266 in __assert_fail_base (fmt=0x7ff3678cfe68 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n",
    assertion=assertion@entry=0xf92ec8 "(bytes_read == (data_written - ((old_pre_checksum_fd || (description_event->checksum_alg == BINLOG_CHECKSUM_ALG_OFF)) ? 0 : 4))) || ((bytes_read == (data_written -1 - (old_pre_checksum_fd || (descript"...,
    file=file@entry=0xf8f940 "/git/PS-5.6-trunk_dbg/sql/log_event.cc", line=line@entry=7852,
    function=function@entry=0xf95fc0 <User_var_log_event::User_var_log_event(char const*, unsigned int, Format_description_log_event const*)::__PRETTY_FUNCTION__> "User_var_log_event::User_var_log_event(const char*, uint, const Format_description_log_event*)")
    at assert.c:92
#7 0x00007ff36777d312 in __GI___assert_fail (
    assertion=0xf92ec8 "(bytes_read == (data_written - ((old_pre_checksum_fd || (description_event->checksum_alg == BINLOG_CHECKSUM_ALG_OFF)) ? 0 : 4))) || ((bytes_read == (data_written -1 - (old_pre_checksum_fd || (descript"...,
    file=0xf8f940 "/git/PS-5.6-trunk_dbg/sql/log_event.cc", line=7852,
    function=0xf95fc0 <User_var_log_event::User_var_log_event(char const*, unsigned int, Format_description_log_event const*)::__PRETTY_FUNCTION__> "User_var_log_event::User_var_log_event(const char*, uint, const Format_description_log_event*)") at assert.c:101
#8 0x0000000000a304aa in User_var_log_event::User_var_log_event (this=0x7ff3218ef500, buf=0x7ff32181a268 "", event_len=43,
    description_event=0x7ff32188d600) at /git/PS-5.6-trunk_dbg/sql/log_event.cc:7842
#9 0x0000000000a22447 in Log_event::read_l...

[Laurynas Biveinis (laurynas-biveinis)]

Already discovered and being fixed by Zsolt

[Zsolt Parragi (zsolt.parragi)]

https://github.com/percona/percona-server/pull/2006

[Shahriyar Rzayev (rzayev-sehriyar)]

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PS-1131