Details
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Bug
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Status: Closed (View Workflow)
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Critical
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Resolution: Fixed
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10.2(EOL), 10.3(EOL)
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None
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Arch Linux, Ubuntu
Description
Test Case
--source include/master-slave.inc
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--connection slave
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--source include/stop_slave.inc
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--let $old_parallel= `select @@GLOBAL.slave_parallel_threads`
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SET GLOBAL slave_parallel_threads=8;
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--source include/start_slave.inc
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--let $rpl_server_no= 2
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--source include/rpl_restart_server.inc
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--connection slave
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--eval SET GLOBAL slave_parallel_threads= $old_parallel
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--source include/start_slave.inc
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--source include/rpl_end.inc
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It does not fail in 10.5
Failure
rpl.tmp 'mix' [ fail ] Found warnings/errors in server log file!
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Test ended at 2021-04-05 09:19:24
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line
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mysqld: sql/sql_list.h:642: void ilink::assert_linked(): Assertion `prev != 0 && next != 0' failed.
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mysqld: sql/sql_list.h:642: void ilink::assert_linked(): Assertion `prev != 0 && next != 0' failed.
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mysqld: sql/sql_list.h:642: void ilink::assert_linked(): Assertion `prev != 0 && next != 0' failed.
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mysqld: sql/sql_list.h:642: void ilink::assert_linked(): Assertion `prev != 0 && next != 0' failed.
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Attempting backtrace. You can use the following information to find out
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^ Found warnings in /home/sachin/10.3/mysql-test/var/log/mysqld.2.err
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ok
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Attachments
Activity
So the issue is this
We have this kill server thread which calls close_connections()
/*
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Force remaining threads to die by closing the connection to the client
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This will ensure that threads that are waiting for a command from the
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client on a blocking read call are aborted.
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*/
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for (;;)
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{
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mysql_mutex_lock(&LOCK_thread_count); // For unlink from list
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if (!(tmp=threads.get()))
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{
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mysql_mutex_unlock(&LOCK_thread_count);
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break;
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}
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when we call threads.get() , It unlinks the elements from link link as it returns
inline struct ilink *get()
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{
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struct ilink *first_link=first;
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if (first_link == &last)
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return 0;
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first_link->unlink(); // Unlink from list
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return first_link;
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}
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inline void unlink()
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{
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/* Extra tests because element doesn't have to be linked */
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if (prev) *prev= next;
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if (next) next->prev=prev;
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prev=0 ; next=0;
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}
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But in handle_rpl_parallel_thread, when we call
THD_CHECK_SENTRY(thd);
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unlink_not_visible_thd(thd);
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delete thd;
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inline void unlink_not_visible_thd(THD *thd)
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{
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thd->assert_linked();
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mysql_mutex_lock(&LOCK_thread_count);
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thd->unlink();
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mysql_mutex_unlock(&LOCK_thread_count);
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}
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inline void assert_linked()
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{
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DBUG_ASSERT(prev != 0 && next != 0);
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}
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So if threads.get() in close connection is called before worker threads gets time to clean up we will get this assert failure
It does not fail in 10.1 , In 10.1 we use
thd->unlink();
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instead of assert on unlinking
With rr it gives different call stack
(rr) bt#0 0x0000000070000002 in ?? ()#1 0x00007f4fce94c473 in _raw_syscall () at src/preload/raw_syscall.S:120#2 0x00007f4fce94a477 in traced_raw_syscall (call=0x7f4f9cdfafa0) at src/preload/syscallbuf.c:274#3 syscall_hook_internal (call=0x7f4f9cdfafa0) at src/preload/syscallbuf.c:3330#4 syscall_hook (call=0x7f4f9cdfafa0) at src/preload/syscallbuf.c:3364#5 0x00007f4fce947330 in _syscall_hook_trampoline () at src/preload/syscall_hook.S:313#6 0x00007f4fce94738f in __morestack () at src/preload/syscall_hook.S:458#7 0x00007f4fce947396 in _syscall_hook_trampoline_48_3d_01_f0_ff_ff () at src/preload/syscall_hook.S:472#8 0x00007f4fcdf21201 in kill () from /usr/lib/libc.so.6#9 0x0000555c5d145f23 in handle_fatal_signal (sig=6) at sql/signal_handler.cc:367#10 <signal handler called>#11 0x0000555c5d9d8f4f in my_timer_cycles () at mysys/my_rdtsc.c:170#12 0x0000555c5d94fc97 in end_mutex_wait_v1 (locker=0x7f4f9d5fad00, rc=0) at storage/perfschema/pfs.cc:3488#13 0x0000555c5d3a2de3 in PolicyMutex<TTASEventMutex<GenericPolicy> >::pfs_end (this=0x555c5e2a5658 <srv_sys+152>, locker=0x7f4f9d5fad00, ret=0) at storage/innobase/include/ib0mutex.h:738#14 0x0000555c5d3a0e61 in PolicyMutex<TTASEventMutex<GenericPolicy> >::enter (this=0x555c5e2a5658 <srv_sys+152>, n_spins=30, n_delay=4, name=0x555c5dcf91a8 "storage/innobase/srv/srv0srv.cc", line=944) at storage/innobase/include/ib0mutex.h:596#15 0x0000555c5d591b28 in srv_release_threads (type=SRV_WORKER, n=3) at storage/innobase/srv/srv0srv.cc:944#16 0x0000555c5d5963c7 in srv_purge_coordinator_thread (arg=0x0) at storage/innobase/srv/srv0srv.cc:2797#17 0x00007f4fce90a299 in start_thread () from /usr/lib/libpthread.so.0#18 0x00007f4fcdfe3053 in clone () from /usr/lib/libc.so.6