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authorPaul Smith <psmith@gnu.org>1999-08-01 08:12:06 +0000
committerPaul Smith <psmith@gnu.org>1999-08-01 08:12:06 +0000
commite34540f79be9c915ce1d6191575267066370f6ec (patch)
tree8418cbb560875512845504a0bd504db81cf4232e /ChangeLog
parent09f1e4cf83853e3636a19da17e28e7291aac9bbd (diff)
downloadgunmake-e34540f79be9c915ce1d6191575267066370f6ec.tar.gz
* Release 3.77.92.3.77.92
* Complete implementation of new jobserver algorithm. * A few minor fixups.
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+1999-08-01 Paul D. Smith <psmith@gnu.org>
+
+ New jobserver algorithm to avoid a possible hole where we could
+ miss SIGCHLDs and get into a deadlock. The original algorithm was
+ suggested by Roland McGrath with a nice refinement by Paul Eggert.
+ Many thanks as well to Tim Magill and Howard Chu, who also
+ provided many viable ideas and critiques. We all had a fun week
+ dreaming up interesting ways to use and abuse UNIX syscalls :).
+
+ Previously we could miss a SIGCHLD if it happened after we reaped
+ the children but before we re-entered the blocking read. If this
+ happened to all makes and/or all children, make would never wake
+ up.
+
+ We avoid this by having the SIGCHLD handler reset the blocking bit
+ on the jobserver pipe read FD (normally read does block in this
+ algorithm). Now if the handler is called between the time we reap
+ and the time we read(), and there are no tokens available, the
+ read will merely return with EAGAIN instead of blocking.
+
+ * main.c (main): Set the blocking bit explicitly here.
+ * job.c (child_handler): If we have a jobserver pipe, set the
+ non-blocking bit for it.
+ (start_waiting_job): Move the token stuff back to new_job; if we
+ do it here then we're not controlling the number of remote jobs
+ started!
+ (new_job): Move the check for job slots to _after_ we've created a
+ child structure. If the read returns without getting a token, set
+ the blocking bit then try to reap_children.
+
+ * make.h (EINTR_SET): Define to test errno if EINTR is available,
+ or 0 otherwise. Just some code cleanup.
+ * arscan.c (ar_member_touch): Use it.
+ * function.c (func_shell): Use it.
+ * job.c (reap_children): Use it.
+ * remake.c (touch_file): Use it.
+
1999-07-28 Paul D. Smith <psmith@gnu.org>
- * make.h: Define _() and N_() macros as a passthrough to initiate
+ * make.h: Define _() and N_() macros as passthrough to initiate
NLS support.
* <all>: Add _()/N_() around translatable strings.