/0001-Whitespace-tabs-to-spaces.patch
Created Jun 25, 2012
Patch to unicorn example init script: better upgrade task
| From 233f504a39aca6e8b2d9332ef324b4c5cc397eca Mon Sep 17 00:00:00 2001 | |
| From: Aaron Suggs <aaron@ktheory.com> | |
| Date: Fri, 6 Apr 2012 18:35:38 -0400 | |
| Subject: [PATCH 1/2] Whitespace: tabs to spaces | |
| --- | |
| examples/init.sh | 90 +++++++++++++++++++++++++++--------------------------- | |
| 1 files changed, 45 insertions(+), 45 deletions(-) | |
| diff --git a/examples/init.sh b/examples/init.sh | |
| index 1f0e035..e8f768a 100644 | |
| --- a/examples/init.sh | |
| +++ b/examples/init.sh | |
| @@ -19,56 +19,56 @@ old_pid="$PID.oldbin" | |
| cd $APP_ROOT || exit 1 | |
| sig () { | |
| - test -s "$PID" && kill -$1 `cat $PID` | |
| + test -s "$PID" && kill -$1 `cat $PID` | |
| } | |
| oldsig () { | |
| - test -s $old_pid && kill -$1 `cat $old_pid` | |
| + test -s $old_pid && kill -$1 `cat $old_pid` | |
| } | |
| case $action in | |
| -start) | |
| - sig 0 && echo >&2 "Already running" && exit 0 | |
| - $CMD | |
| - ;; | |
| -stop) | |
| - sig QUIT && exit 0 | |
| - echo >&2 "Not running" | |
| - ;; | |
| -force-stop) | |
| - sig TERM && exit 0 | |
| - echo >&2 "Not running" | |
| - ;; | |
| -restart|reload) | |
| - sig HUP && echo reloaded OK && exit 0 | |
| - echo >&2 "Couldn't reload, starting '$CMD' instead" | |
| - $CMD | |
| - ;; | |
| -upgrade) | |
| - if sig USR2 && sleep 2 && sig 0 && oldsig QUIT | |
| - then | |
| - n=$TIMEOUT | |
| - while test -s $old_pid && test $n -ge 0 | |
| - do | |
| - printf '.' && sleep 1 && n=$(( $n - 1 )) | |
| - done | |
| - echo | |
| + start) | |
| + sig 0 && echo >&2 "Already running" && exit 0 | |
| + $CMD | |
| + ;; | |
| + stop) | |
| + sig QUIT && exit 0 | |
| + echo >&2 "Not running" | |
| + ;; | |
| + force-stop) | |
| + sig TERM && exit 0 | |
| + echo >&2 "Not running" | |
| + ;; | |
| + restart|reload) | |
| + sig HUP && echo reloaded OK && exit 0 | |
| + echo >&2 "Couldn't reload, starting '$CMD' instead" | |
| + $CMD | |
| + ;; | |
| + upgrade) | |
| + if sig USR2 && sleep 2 && sig 0 && oldsig QUIT | |
| + then | |
| + n=$TIMEOUT | |
| + while test -s $old_pid && test $n -ge 0 | |
| + do | |
| + printf '.' && sleep 1 && n=$(( $n - 1 )) | |
| + done | |
| + echo | |
| - if test $n -lt 0 && test -s $old_pid | |
| - then | |
| - echo >&2 "$old_pid still exists after $TIMEOUT seconds" | |
| - exit 1 | |
| - fi | |
| - exit 0 | |
| - fi | |
| - echo >&2 "Couldn't upgrade, starting '$CMD' instead" | |
| - $CMD | |
| - ;; | |
| -reopen-logs) | |
| - sig USR1 | |
| - ;; | |
| -*) | |
| - echo >&2 "Usage: $0 <start|stop|restart|upgrade|force-stop|reopen-logs>" | |
| - exit 1 | |
| - ;; | |
| + if test $n -lt 0 && test -s $old_pid | |
| + then | |
| + echo >&2 "$old_pid still exists after $TIMEOUT seconds" | |
| + exit 1 | |
| + fi | |
| + exit 0 | |
| + fi | |
| + echo >&2 "Couldn't upgrade, starting '$CMD' instead" | |
| + $CMD | |
| + ;; | |
| + reopen-logs) | |
| + sig USR1 | |
| + ;; | |
| + *) | |
| + echo >&2 "Usage: $0 <start|stop|restart|upgrade|force-stop|reopen-logs>" | |
| + exit 1 | |
| + ;; | |
| esac | |
| -- | |
| 1.7.4.4 |
| From d4d34eff222dad71c150f0e990a474af143fa3e7 Mon Sep 17 00:00:00 2001 | |
| From: Aaron Suggs <aaron@ktheory.com> | |
| Date: Fri, 6 Apr 2012 18:41:47 -0400 | |
| Subject: [PATCH 2/2] Better upgrade script in example init script | |
| Removes the sleep while waiting for the new pid file to be written. | |
| (This could be problematic on busy or small servers) | |
| When preload_app is enabled, reduces the time requests hang while | |
| waiting for the new workers. | |
| --- | |
| examples/init.sh | 16 +++++++++++++++- | |
| 1 files changed, 15 insertions(+), 1 deletions(-) | |
| diff --git a/examples/init.sh b/examples/init.sh | |
| index e8f768a..3d1ba01 100644 | |
| --- a/examples/init.sh | |
| +++ b/examples/init.sh | |
| @@ -45,8 +45,22 @@ case $action in | |
| $CMD | |
| ;; | |
| upgrade) | |
| - if sig USR2 && sleep 2 && sig 0 && oldsig QUIT | |
| + if sig USR2 | |
| then | |
| + printf 'Waiting for new workers' | |
| + n=$TIMEOUT | |
| + while (! (test -s $PID && ps --no-headers --ppid `cat $PID` > /dev/null)) && test $n -ge 0 | |
| + do | |
| + printf '.' && sleep 1 && n=$(( $n - 1 )) | |
| + done | |
| + if test ! -s $old_pid | |
| + then | |
| + echo | |
| + echo >&2 'New workers failed to start; see error log' | |
| + exit 1 | |
| + fi | |
| + | |
| + printf '\nStopping old master' && oldsig QUIT | |
| n=$TIMEOUT | |
| while test -s $old_pid && test $n -ge 0 | |
| do | |
| -- | |
| 1.7.4.4 |
| I've been using the example init.sh script distributed with unicorn. | |
| It works very well, but I ran in to some rough edges with the | |
| `upgrade` task (which my organization runs several times per day when | |
| deploying new code). | |
| The salient part of the current upgrade task is: | |
| sig USR2 && sleep 2 && sig 0 && oldsig QUIT | |
| # then wait for the old pid to disappear | |
| We found that on tiny or busy servers, the "sleep 2" was too short. A | |
| too short sleep leaves the server in an undesirable state. The init | |
| script fails, and both the old and new unicorn processes are running. | |
| To resolve, I'd manually send a QUIT to the old master to clean things | |
| up. | |
| We tried increasing the sleep time, and this issue became less common, | |
| but still happens. I'd like to avoid the sleep altogether. | |
| Second, the old workers are terminated before the new workers are | |
| ready to handle requests. This causes requests to hang (for about 25 | |
| seconds in our case) until the app is loaded and the new workers begin | |
| responding to requests. I'd like to minimize the impact that code | |
| deploys have on our app's performance. | |
| With this patch, the `upgrade` task: | |
| 1. Sends a USR2 signal to the current (old) master. This seems to | |
| immediately rename the pid to pid.oldbin. | |
| 2. Waits for the master pid to exist, and for that process to have | |
| children. When preload_app is true, the presence of child processes | |
| means that those workers are nearly ready to handle requests (afaik, | |
| they just need to execute the after_fork block) | |
| 3. Once the master process has children, send a QUIT to the old | |
| master. (If the old master is already gone, that means the new master | |
| failed to start. Exit with an error. Otherwise, wait for the old | |
| master to spin down.) | |
| Caveats: with my patch, it's more likely that for a second both old | |
| any new workers are responding to requests. We find that this doesn't | |
| usually happen, and it's not bad if it does. The way I find child | |
| processes "ps --no-headers --ppid `cat $PID`" is a totally linux-ism. | |
| If someone can suggest a more portable command (OS X, etc), I'd | |
| appreciate it. | |
| I also published the patches on github, if that's your thing: | |
| https://github.com/ktheory/unicorn/tree/better_init | |
| (The first patch converts tabs to spaces, as is common for ruby projects). | |
| I realize this patch may be particular to our use case and may not | |
| generally appropriate. I'd appreciate learning what scripts others use | |
| for fast, reliable unicorn upgrades (capistrano-unicorn gem looks | |
| neat). | |
| Thanks! |
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