Strange error messages in PHP log on azure website

Question

Hi,
I have a PHP website (SMF Forum) that runs for more than a year now (not in one run,  but I never experienced this error before). After complaints about time-outs, blank pages and other odd behavior I found this in the log files:
lots of error messages like this one:
PHP Fatal error:  Failure in Wincache[4280] free_memory: Block 0x3c1827c not in use
And this one:
PHP Fatal error:  WINCACHE: lock_readlock: acquired abandoned mutex Global\FILELIST_CACHE_5.4_1.3.7.4_1_0_850133_X. Something bad happend in another process! in Unknown on line 0
Stopping/starting the website did solve the problem but I am curious what could cause this and if there is something I can do to prevent this.
Best regards,
Arthur

Answer 1

In WinCache 1.3.7.4, I improved the diagnostics & tracing surrounding issues which previously led to memory corruptions in the shared memory segments of the WinCache caches (File, Session, User, Opcode).  Further, I improved detection and avoidance
of AVs in this same area.  The trace messageyou're seeing,  "free_memory: Block <N> not in use", is proof that WinCache detected a corruption (it was attempting to free a shared memory block that wasn't in use), and avoided further
corruption (it didn't try to free the not-free memory block, which would have led to even greater corruption).
The second message, "lock_readlock: acquired abandoned mutex..." indicates that another php-cgi.exe process crashed while holding a mutex that WinCache uses.  In this case, it's the lock for the File cache.
To diagnose, look at the line of PHP code mentioned in the "free_memory: Block <N> not in use" message.  If one of the following functions is on that line, there is a work around:
◦ file_exists 
◦ file_get_contents 
◦ readfile 
◦ is_readable 
◦ is_writable 
◦ is_dir 
◦ realpath 
◦ filesize
If it's one of these functions, then I would recommend setting wincache.reroute_enabled=0 in your .user.ini.
Thx!
    --E.