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Diffstat (limited to 'ChangeLog')
| -rw-r--r-- | ChangeLog | 39 |
1 files changed, 38 insertions, 1 deletions
@@ -1,6 +1,43 @@ +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. |