Changes between Version 8 and Version 9 of TipAndDoc/cron

Timestamp:

May 18, 2010 6:26:15 PM (14 years ago)

Author:

mitty

Comment:

--

TipAndDoc/cron

@@ -9 +9 @@
 {{{
 sleep 15 >/dev/null 2>&1 &
+}}}
+
+ == 問題 ==
+ * 次のようなタスクを登録した場合
+   1. /etc/cron.hourly/1
+{{{
+#!/bin/sh
+
+sleep 60
+touch /tmp/1.$$.`date +%T.%N`
+ls -l /tmp/1*
+}}}
+   1. /etc/cron.hourly/2
+{{{
+#!/bin/sh
+
+sleep 60
+touch /tmp/2.$$.`date +%T.%N`
+ls -l /tmp/2*
+}}}
+   1. /etc/cron.hourly/3
+{{{
+#!/bin/sh
+
+sleep 60
+touch /tmp/3.$$.`date +%T.%N`
+ls -l /tmp/3*
+}}}
+
+ * 1 -> 2 -> 3 と逐次実行されるため、同時並行より遅いタイミングでタスクが処理される
+   1. pstree -ap
+{{{
+  ├─cron,3751
+  │   └─cron,3792
+  │       └─sh,3794 -c    cd / && run-parts --report /etc/cron.hourly
+  │           └─run-parts,3795 --report /etc/cron.hourly
+  │               └─1,3796 /etc/cron.hourly/1
+  │                  └─sleep,3797 60
+}}}
+   1. pstree -ap
+{{{
+  ├─cron,3751
+  │   └─cron,3792
+  │       ├─sendmail,3806 -i -FCronDaemon -oem root
+  │       │   └─postdrop,3809 -r
+  │       └─sh,3794 -c    cd / && run-parts --report /etc/cron.hourly
+  │           └─run-parts,3795 --report /etc/cron.hourly
+  │               └─2,3807 /etc/cron.hourly/2
+  │                  └─sleep,3808 60
+}}}
+   1. pstree -ap
+{{{
+  ├─cron,3751
+  │   └─cron,3792
+  │       ├─sendmail,3806 -i -FCronDaemon -oem root
+  │       │   └─postdrop,3809 -r
+  │       └─sh,3794 -c    cd / && run-parts --report /etc/cron.hourly
+  │           └─run-parts,3795 --report /etc/cron.hourly
+  │               └─3,3816 /etc/cron.hourly/3
+  │                  └─sleep,3817 60
+}}}
+
+ * 実行ログはまとめて配送される
+   * mail
+{{{
+Mail version 8.1.2 01/15/2001.  Type ? for help.
+"/var/mail/mitty": 1 message 1 new
+>N  1 root@lucid.mitty.  Tue May 18 17:20   24/968   Cron <root@lucid>    cd / &
+&
+Message 1:
+From root@lucid.mitty.jp  Tue May 18 17:20:01 2010
+X-Original-To: root
+From: root@lucid.mitty.jp (Cron Daemon)
+To: root@lucid.mitty.jp
+Subject: Cron <root@lucid>    cd / && run-parts --report /etc/cron.hourly
+Content-Type: text/plain; charset=ANSI_X3.4-1968
+X-Cron-Env: <SHELL=/bin/sh>
+X-Cron-Env: <PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin>
+X-Cron-Env: <HOME=/root>
+X-Cron-Env: <LOGNAME=root>
+Date: Tue, 18 May 2010 17:18:01 +0900 (JST)
+
+/etc/cron.hourly/1:
+-rw-r--r-- 1 root root 0 May 18 17:18 /tmp/1.3796.17:18:01.530794512
+/etc/cron.hourly/2:
+-rw-r--r-- 1 root root 0 May 18 17:19 /tmp/2.3807.17:19:01.552276713
+/etc/cron.hourly/3:
+-rw-r--r-- 1 root root 0 May 18 17:20 /tmp/3.3816.17:20:01.573785281
+}}}
+
+ === サブシェルにより解決法 ===
+ * 各タスクを次のようにサブシェル化する
+   1. /etc/cron.hourly/1
+{{{
+#!/bin/sh
+
+(
+sleep 60
+touch /tmp/1.$$.`date +%T.%N`
+ls -l /tmp/1* 2>&1 | mail $LOGNAME
+) >/dev/null 2>&1 &
+}}}
+   1. /etc/cron.hourly/2
+{{{
+#!/bin/sh
+
+(
+sleep 60
+touch /tmp/2.$$.`date +%T.%N`
+ls -l /tmp/2* 2>&1 | mail $LOGNAME
+) >/dev/null 2>&1 &
+}}}
+   1. /etc/cron.hourly/3
+{{{
+#!/bin/sh
+
+(
+sleep 60
+touch /tmp/3.$$.`date +%T.%N`
+ls -l /tmp/3* 2>&1 | mail $LOGNAME
+) >/dev/null 2>&1 &
+}}}
+
+ * 同時実行される
+   *  pstree -ap
+{{{
+  ├─1,3860 /etc/cron.hourly/1
+  │  └─sleep,3865 60
+  ├─2,3862 /etc/cron.hourly/2
+  │  └─sleep,3864 60
+  ├─3,3866 /etc/cron.hourly/3
+  │  └─sleep,3867 60
+
+  ├─cron,3836
+}}}
+
+ * 実行ログはmailコマンドにより個別に配送される
+   * mail
+{{{
+Mail version 8.1.2 01/15/2001.  Type ? for help.
+"/var/mail/mitty": 3 messages 3 new
+>N  1 root@lucid.mitty.  Tue May 18 17:18   13/480
+ N  2 root@lucid.mitty.  Tue May 18 17:18   13/480
+ N  3 root@lucid.mitty.  Tue May 18 17:18   13/480
+&
+Message 1:
+From root@lucid.mitty.jp  Tue May 18 17:18:01 2010
+X-Original-To: root
+To: root@lucid.mitty.jp
+Date: Tue, 18 May 2010 17:18:01 +0900 (JST)
+From: root@lucid.mitty.jp (root)
+
+-rw-r--r-- 1 root root 0 May 18 17:18 /tmp/3.3863.17:18:01.400271817
+
+&
+Message 2:
+From root@lucid.mitty.jp  Tue May 18 17:18:01 2010
+X-Original-To: root
+To: root@lucid.mitty.jp
+Date: Tue, 18 May 2010 17:18:01 +0900 (JST)
+From: root@lucid.mitty.jp (root)
+
+-rw-r--r-- 1 root root 0 May 18 17:18 /tmp/2.3861.17:18:01.397221662
+
+&
+Message 3:
+From root@lucid.mitty.jp  Tue May 18 17:18:01 2010
+X-Original-To: root
+To: root@lucid.mitty.jp
+Date: Tue, 18 May 2010 17:18:01 +0900 (JST)
+From: root@lucid.mitty.jp (root)
+
+-rw-r--r-- 1 root root 0 May 18 17:18 /tmp/1.3859.17:18:01.401215856
 }}}