[automake-commit] branch master updated: doc: original purpose of $sleep is when AC_OUTPUT is not used.

[Karl Berry]

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The following commit(s) were added to refs/heads/master by this push:
     new c09ff1dfd doc: original purpose of $sleep is when AC_OUTPUT is not 
used.
c09ff1dfd is described below

commit c09ff1dfd6d7182ba0a264f89993cc19edb1d98c
Author: Karl Berry <karl@freefriends.org>
AuthorDate: Wed Jun 19 09:01:51 2024 -0700

    doc: original purpose of $sleep is when AC_OUTPUT is not used.
    
    * t/ax/test-defs.in (sleep): mention original purpose of $sleep,
    namely when AC_OUTPUT is not used and hence the sleep done in
    AC_CONFIG_COMMANDS_* is not done:
      https://lists.gnu.org/archive/html/bug-automake/2010-10/msg00000.html
    Discovered by Bruno in his rearch on the "sleep" history:
      https://lists.gnu.org/archive/html/automake/2024-06/msg00054.html
---
 t/ax/test-defs.in | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/t/ax/test-defs.in b/t/ax/test-defs.in
index 61a88110e..aac5d60e3 100644
--- a/t/ax/test-defs.in
+++ b/t/ax/test-defs.in
@@ -217,11 +217,23 @@ case $MTIME_RESOLUTION in
   ;;
 esac
 
-# This sleep variable is used explicitly in some tests to avoid
-# too-quick creation. Seems likely this was an incomplete workaround
-# for this whole subsecond-mtime problem. With this set to "sleep 1",
-# there were still random parallelization failures; setting
-# am_cv_sleep_fractional_seconds=false as above was still needed.
+# This sleep variable is used explicitly in tests when AC_OUTPUT is not
+# used, hence config.status is not created, hence AC_CONFIG_COMMANDS_*
+# is not evaluated. Originally set up here:
+#   https://lists.gnu.org/archive/html/bug-automake/2010-10/msg00000.html
+# Discovered again in this review of the "sleep" history:
+#   https://lists.gnu.org/archive/html/automake/2024-06/msg00054.html
+# It seems a better fix would be to have Automake (in sanity.m4) figure
+# out the need for sleep even when AC_OUTPUT is not used.
+# 
+# In general, the problem is when the mtime resolution is 1 second (or
+# more) and the configure file is created less than 1 second ago, which
+# happens routinely in the tests, and for many fast-enough configure
+# scripts in other packages, too.
+# 
+# At any rate, with this set to "sleep 1", there were still random
+# parallelization failures; setting am_cv_sleep_fractional_seconds=false
+# as above was still needed.
 #
 sleep="sleep $MTIME_RESOLUTION"