K 10
svn:author
V 3
kib
K 8
svn:date
V 27
2012-09-22T12:17:09.197832Z
K 7
svn:log
V 773
Do not skip two elements of the tid_buffer when reusing the buffer
slot. This eventually results in exhaustion of the tid space, causing
new threads get tid -1 as identifier.

The bad effect of having the thread id equal to -1 is that
UMTX_OP_UMUTEX_WAIT returns EFAULT for a lock owned by such thread,
because casuword cannot distinguish between literal value -1 read from
the address and -1 returned as an indication of faulted
access. _thr_umutex_lock() helper from libthr does not check for
errors from _umtx_op_err(2), causing an infinite loop in
mutex_lock_sleep().

We observed the JVM processes hanging and consuming enormous amount of
system time on machines with approximately 100 days uptime.

Reported by:	Mykola Dzham <freebsd levsha org ua>
MFC after:	1 week

END