Fibers 1.0.0 has a bug in run-fibers in which peer schedulers aren't destroyed -
so if you had 4 cores, 1 would be destroyed when run-fibers returned, but the
other 3 would stay around.  Each scheduler uses 3 file descriptors, so for
machines with many cores, this resource leak adds up quickly - quickly enough
that the test suite can even fail because of it.

See https://github.com/wingo/fibers/issues/36.

This fixes that.  It should be safe to destroy the peer schedulers at the given
point because the threads that could be running them are all either dead or the
current thread.

As of May 21, 2020, this bug still existed in the 1.0.0 (latest) release and in
git master.
--- a/fibers.scm	2020-05-21 18:38:06.890690154 -0500
+++ b/fibers.scm	2020-05-21 18:38:56.395686693 -0500
@@ -137,5 +137,6 @@
              (%run-fibers scheduler hz finished? affinity))
            (lambda ()
              (stop-auxiliary-threads scheduler)))))
+      (for-each destroy-scheduler (scheduler-remote-peers scheduler))
       (destroy-scheduler scheduler)
       (apply values (atomic-box-ref ret))))))

54209a1c08524374c'>refs</a><a class='active' href='/guix/log/gnu/system/uuid.scm'>log</a><a href='/guix/tree/gnu/system/uuid.scm?id=79624befa1a41e0ea237a4654209a1c08524374c'>tree</a><a href='/guix/commit/gnu/system/uuid.scm?id=79624befa1a41e0ea237a4654209a1c08524374c'>commit</a><a href='/guix/diff/gnu/system/uuid.scm?id=79624befa1a41e0ea237a4654209a1c08524374c'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/system/uuid.scm'>
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<div class='path'>path: <a href='/guix/log/?id=79624befa1a41e0ea237a4654209a1c08524374c'>root</a>/<a href='/guix/log/gnu?id=79624befa1a41e0ea237a4654209a1c08524374c'>gnu</a>/<a href='/guix/log/gnu/system?id=79624befa1a41e0ea237a4654209a1c08524374c'>system</a>/<a href='/guix/log/gnu/system/uuid.scm?id=79624befa1a41e0ea237a4654209a1c08524374c'>uuid.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/system/uuid.scm?id=79624befa1a41e0ea237a4654209a1c08524374c&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-07-26 18:35:10 +0200'>2020-07-26</span></td><td><a href='/guix/commit/gnu/system/uuid.scm?id=675e56221e3dfc58cac94bf30835f16a9c41d530'>file-systems: Add NTFS support.</a><span class='msg-avail'>...</span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2020-06-18 23:24:37 -0400'>2020-06-18</span></td><td><a href='/guix/commit/gnu/system/uuid.scm?id=04a4af6dd4fbfcfc564eac5eafe647b192ba3a8f'>uuid: Prevent a loop on invalid arguments.</a><span class='msg-avail'>...</span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2020-01-03 13:54:13 +0100'>2020-01-03</span></td><td><a href='/guix/commit/gnu/system/uuid.scm?id=43c4d27cdfed5ce98ecd4ce48fcd43e188e5a3aa'>uuid: Add support for JFS.</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2019-05-07 12:18:44 +0200'>2019-05-07</span></td><td><a href='/guix/commit/gnu/system/uuid.scm?id=6c5790a2faf8ffc401e43b13425a707394e40874'>uuid: 'fat-uuid-&gt;string' preserves leading zeros.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
l 'deduplicate' only when SIZE is greater than
%DEDUPLICATION-MINIMUM-SIZE; otherwise call 'dump-port'.
* nix/libstore/gc.cc (LocalStore::removeUnusedLinks): Drop files where
st.st_size &lt; deduplicationMinSize.
* nix/libstore/local-store.hh (deduplicationMinSize): New declaration.
* nix/libstore/optimise-store.cc (deduplicationMinSize): New variable.
(LocalStore::optimisePath_): Return when PATH is a symlink or smaller
than 'deduplicationMinSize'.
* tests/derivations.scm ("identical files are deduplicated"): Produce
files bigger than %DEDUPLICATION-MINIMUM-SIZE.
* tests/nar.scm ("restore-file-set with directories (signed, valid)"):
Likewise.
* tests/store-deduplication.scm ("deduplicate, below %deduplication-minimum-size"):
New test.
("deduplicate", "deduplicate, ENOSPC"): Produce files bigger than
%DEDUPLICATION-MINIMUM-SIZE.
* tests/store.scm ("substitute, deduplication"): Likewise.


</td></tr>
<tr class='logheader'><td><span title='2021-06-18 11:25:41 +0100'>2021-06-18</span></td><td class='logsubject'><a href='/guix/commit/config-daemon.ac?id=4985a4272497bf9ba87a2190353d915da9b55906'>Start enabling substitutes from bordeaux.guix.gnu.org.</a></td><td>Christopher Baines</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
In addition to substitutes from ci.guix.gnu.org.  There are more changes that
can be made in the future, but these changes seem like a good start.

* config-daemon.ac (guix_substitute_urls): Add https://bordeaux.guix.gnu.org.
* guix/scripts/substitute.scm (%default-substitute-urls): Add
http://bordeaux.guix.gnu.org.
* guix/store.scm (%default-substitute-urls): Add bordeaux.guix.gnu.org.
* doc/guix.texi: Adjust accordingly.
* doc/contributing.texi: Adjust accordingly.


</td></tr>
<tr class='logheader'><td><span title='2020-12-11 19:06:53 +0100'>2020-12-11</span></td><td class='logsubject'><a href='/guix/commit/config-daemon.ac?id=26b1030012837ff3f91d2a39971358180324d730'>maint: Remove unused 'NIX_VERSION' macro.</a></td><td>Ludovic Courtès</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
* config-daemon.ac: Do not define NIX_VERSION.


</td></tr>
<tr class='logheader'><td><span title='2020-12-11 19:06:53 +0100'>2020-12-11</span></td><td class='logsubject'><a href='/guix/commit/config-daemon.ac?id=dbdae9f96f11a006993b659e0e7fd5cbf467f844'>maint: Avoid macros obsolete in Autoconf 2.70.</a></td><td>Ludovic Courtès</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
* configure.ac: Require Autoconf 2.69.  Use 'AS_HELP_STRING' instead of
'AC_HELP_STRING'.
* m4/guix.m4: Likewise.
* config-daemon.ac: Use 'AC_CONFIG_HEADERS' instead of the singular
variant.


</td></tr>