URL:
<http://savannah.gnu.org/bugs/?47995>
Summary: Parallel double-colon breaks FORCE
Project: make
Submitted by: joecrayne
Submitted on: Tue 24 May 2016 06:04:48 AM GMT
Severity: 3 - Normal
Item Group: Bug
Status: None
Privacy: Public
Assigned to: None
Open/Closed: Open
Discussion Lock: Any
Component Version: None
Operating System: POSIX-Based
Fixed Release: None
Triage Status: None
_______________________________________________________
Details:
This issue was reported on the mailing list
<http://lists.gnu.org/archive/html/bug-make/2016-05/msg00041.html> as a
failure when building git in parallel which uses double-colons to make
multiple recipes run. It was traced to my patch submitted in bug 44742. Here
is a minimal test case:
+verbatum+
all::
@echo one
all:: joe
@echo four
joe: FORCE
touch joe-is-forced
FORCE:
# $ make
# one
# touch joe-is-forced
# four
#
# $ make -j
# one
# four
-verbatum-
Debug messages show that the "joe" target was erroneously pruned by this
apparent optimization:
+verbatum+
/* Prune the dependency graph: if we've already been here on _this_
pass through the dependency graph, we don't have to go any further.
We won't reap_children until we start the next pass, so no state
change is possible below here until then. */
if (f->considered == considered)
{
/* Check for the case where a target has been tried and failed but
the diagnostics haven't been issued. If we need the diagnostics
then we will have to continue. */
if (!(f->updated && f->update_status > us_none
&& !f->dontcare && f->no_diag))
{
DBF (DB_VERBOSE, _("Pruning file '%s'.\n"));
return f->command_state == cs_finished ? f->update_status :
us_success;
}
}
-verbatum-
I believe this is based on an assumption that I've rendered false. I'm having
trouble understanding how it was true in the first place.
An easy fix would be to elide this optimization in the case of parallel
double-colon builds.
Paul if you understand the issue better, I'd appreciate your thoughts on it.
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