Date: Mon, 26 Jan 1998 10:41:27 -0800 (PST) From: Matt Dillon <dillon@best.net> To: FreeBSD-gnats-submit@FreeBSD.ORG Subject: bin/5572: major time step blows cron up Message-ID: <199801261841.KAA10811@flea.best.net>
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>Number: 5572
>Category: bin
>Synopsis: A major time step blows cron up, runs thousands of processes
>Confidential: no
>Severity: critical
>Priority: high
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Mon Jan 26 10:50:00 PST 1998
>Last-Modified:
>Originator: Matt Dillon
>Organization:
Best Internet Communications
>Release: FreeBSD 2.2.5-STABLE i386
>Environment:
Loaded shell machines with lots of accounts and lots of cron
jobs.
>Description:
If a major time step occurs, for example a backwards time step,
cron will attempt to run every single job in between. This
can result in cron starting thousands of jobs for the last N
hours or N days, depending on how large a time step occured.
>How-To-Repeat:
Create some cron jobs and set the time backwards by a few hours.
>Fix:
The fix is included below. We check for nonsensical time steps
and deal with them by resynchronizing cron's internal time
tracking.
*** LINK/cron.c Wed Sep 17 15:10:45 1997
--- cron.c Mon Jan 26 10:36:26 1998
***************
*** 229,234 ****
--- 229,248 ----
cron_sleep() {
register int seconds_to_wait;
+ /*
+ * Look for time step and don't run all the friggin cron jobs in
+ * between if a major backwards step occurs. Otherwise, a major
+ * time step (e.g. if the time gets messed up on the machine) may
+ * cause thousands of cron jobs to be run, especially if you have a lot
+ * of users.
+ */
+
+ seconds_to_wait = (int) (TargetTime - time((time_t*)0));
+
+ if (seconds_to_wait < -600 || seconds_to_wait > 600) {
+ cron_sync();
+ }
+
do {
seconds_to_wait = (int) (TargetTime - time((time_t*)0));
Debug(DSCH, ("[%d] TargetTime=%ld, sec-to-wait=%d\n",
>Audit-Trail:
>Unformatted:
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