On PPC64 high-loaded server may crash due to assertion failure in InnoDB
rwlocks code.
This happened because load order between "recursive" and "writer_thread"
wasn't properly enforced.
The bug was that full memory barrier was missing in the code that ensures that
a waiter on an InnoDB mutex will not go to sleep unless it is guaranteed to be
woken up again by another thread currently holding the mutex. This made
possible a race where a thread could get stuck waiting for a mutex that is in
fact no longer locked. If that thread was also holding other critical locks,
this could stall the entire server. There is an error monitor thread than can
break the stall, it runs about once per second. But if the error monitor
thread itself got stuck or was not running, then the entire server could hang
infinitely.
This was introduced on i386/amd64 platforms in 5.5.40 and 10.0.13 by an
incorrect patch that tried to fix the similar problem for PowerPC.
This commit reverts the incorrect PowerPC patch, and instead implements a fix
for PowerPC that does not change i386/amd64 behaviour, making PowerPC work
similarly to i386/amd64.
MDEV-6483 - Deadlock around rw_lock_debug_mutex on PPC64
This problem affects only debug builds on PPC64.
There are at least two race conditions around
rw_lock_debug_mutex_enter and rw_lock_debug_mutex_exit:
- rw_lock_debug_waiters was loaded/stored without setting
appropriate locks/memory barriers.
- there is a gap between calls to os_event_reset() and
os_event_wait() and in such case we're supposed to pass
return value of the former to the latter.
Fixed by replacing self-cooked spinlocks with system mutexes.
These days system mutexes offer much better performance. OTOH
performance is not that critical for debug builds.
Part of this work is based on Stewart Smitch's memory barrier and lower priori
patches for power8.
- Added memory syncronization for innodb & xtradb for power8.
- Added HAVE_WINDOWS_MM_FENCE to CMakeList.txt
- Added os_isync to fix a syncronization problem on power
- Added log_get_lsn_nowait which is now used srv_error_monitor_thread to ensur
if log mutex is locked.
All changes done both for InnoDB and Xtradb
InnoDB: Failing assertion: mutex_own(&buf_pool->LRU_list_mutex)
and
InnoDB: Assertion failure in thread 2868898624 in file buf0lru.c line 1077
InnoDB: Failing assertion: mutex_own(&buf_pool->LRU_list_mutex)
Analysis: Function buf_LRU_free_block might release LRU_list_mutex on
same cases to avoid mutex order problems, we need to take it back
before accessing list.
include/my_sys.h:
Move generic file parsing functions out to shared code, as they are used in several places.
mysys/mf_iocache2.c:
Move generic file parsing functions out to shared code, as they are used in several places.
sql/log_event.cc:
Fix XtraDB build with embedded server.
XtraDB needs access to replication stuff, which is missing in embedded server.
Solved by defining wrapper function for this which is compiled differently for normal and
embedded case.
sql/log_event.h:
Fix XtraDB build with embedded server.
XtraDB needs access to replication stuff, which is missing in embedded server.
Solved by defining wrapper function for this which is compiled differently for normal and
embedded case.
sql/slave.cc:
Move generic file parsing functions out to shared code, as they are used in several places.
