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Posted to issues@solr.apache.org by GitBox <gi...@apache.org> on 2021/08/07 11:39:47 UTC
[GitHub] [solr] colvinco opened a new pull request #250: SOLR-15558: Identify zombie processes when stopping
colvinco opened a new pull request #250:
URL: https://github.com/apache/solr/pull/250
https://issues.apache.org/jira/browse/SOLR-15558
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# Description
Identify zombie processes when stopping Solr, since a zombie has already terminated there is no need to wait 3 minutes.
Also simplified some of the other `ps` usage to filter by id rather than `grep`ing.
# Solution
`ps -o stat --no-headers $SOLR_PID` will output the STAT for a process (if it is running). If the process is a Zombie/defunct then the stat will be `Z`. If the process isn't running then no output will be generated.
Also simplified some of the other `ps` usage to filter by id rather than `grep`ing.
GitHub makes the diff look bigger than it is
# Tests
Manually checked on Ubuntu 16.04.6 in a docker container, by starting and stopping Solr.
When running `solr stop` inside a container that was started with `docker run -dit <image> tail -f /dev/null` [the docker PID 1 reaping problem occurs](https://issues.apache.org/jira/browse/SOLR-15558) and the following output is generated without this patch (and 3 minutes elapses):
```
root@6683526ba504:/opt/solr-8.9.0# bin/solr stop
Sending stop command to Solr running on port 8983 ... waiting up to 180 seconds to allow Jetty process 454 to stop gracefully.
Solr process 454 is still running; jattach threaddumping it now.
Could not start attach mechanism: No such file or directory
Solr process 454 is still running; forcefully killing it now.
Killed process 454
ERROR: Failed to kill previous Solr Java process 454 ... script fails.
```
with this patch:
```
root@b457f11bf485:/opt/solr-8.9.0# bin/solr stop
Sending stop command to Solr running on port 8983 ... waiting up to 180 seconds to allow Jetty process 2288 to stop gracefully.
Solr process 2288 has terminated abnormally. Solr has exited but a zombie process entry remains.
```
On a container that is started with `docker run -dit --init <image> tail -f /dev/null` the reaping problem doesn't occur and the following output is generated with or without the patch and the process terminates normally:
```
root@262baa4c3c28:/opt/solr-8.9.0# bin/solr stop
Sending stop command to Solr running on port 8983 ... waiting up to 180 seconds to allow Jetty process 135 to stop gracefully.
```
# Checklist
Please review the following and check all that apply:
- [x] I have reviewed the guidelines for [How to Contribute](https://wiki.apache.org/solr/HowToContribute) and my code conforms to the standards described there to the best of my ability.
- [x] I have created a Jira issue and added the issue ID to my pull request title.
- [x] I have given Solr maintainers [access](https://help.github.com/en/articles/allowing-changes-to-a-pull-request-branch-created-from-a-fork) to contribute to my PR branch. (optional but recommended)
- [x] I have developed this patch against the `main` branch.
- [ ] I have run `./gradlew check`.
- [ ] I have added tests for my changes.
- [ ] I have added documentation for the [Reference Guide](https://github.com/apache/solr/tree/main/solr/solr-ref-guide)
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[GitHub] [solr] colvinco commented on pull request #250: SOLR-15558: Identify zombie processes when stopping
Posted by GitBox <gi...@apache.org>.
colvinco commented on pull request #250:
URL: https://github.com/apache/solr/pull/250#issuecomment-1028142035
Yes that seems to work fine. I've used `stat=''` rather than `stat= ` to try and be a bit more verbose, hopefully that works everywhere.
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[GitHub] [solr] madrob commented on pull request #250: SOLR-15558: Identify zombie processes when stopping
Posted by GitBox <gi...@apache.org>.
madrob commented on pull request #250:
URL: https://github.com/apache/solr/pull/250#issuecomment-1027097574
This doesn't work on my local macOS Monterey 12.2
```
$ ps -o stat --no-headers 30425
ps: illegal option -- -
usage: ps [-AaCcEefhjlMmrSTvwXx] [-O fmt | -o fmt] [-G gid[,gid...]]
[-g grp[,grp...]] [-u [uid,uid...]]
[-p pid[,pid...]] [-t tty[,tty...]] [-U user[,user...]]
ps [-L]
```
However, the following seems to work:
```
$ ps -o stat= 30425
S
```
Can you check if this same syntax will work on Linux?
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[GitHub] [solr] iMichka commented on pull request #250: SOLR-15558: Identify zombie processes when stopping
Posted by GitBox <gi...@apache.org>.
iMichka commented on pull request #250:
URL: https://github.com/apache/solr/pull/250#issuecomment-1026260307
Hi. I am maintainer of Homebrew, a package manager for macOS and Linux.
We build and test `solr` in docker, and we have been hit by this issue.
I tested your patch https://github.com/Homebrew/homebrew-core/pull/94188 and it fixed the failure.
The tests also pass on the 3 macOS versions we build for. CI is still running but it already looks good on our side.
Can this PR be reviewed and maybe included in the next release?
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[GitHub] [solr] colvinco commented on a change in pull request #250: SOLR-15558: Identify zombie processes when stopping
Posted by GitBox <gi...@apache.org>.
colvinco commented on a change in pull request #250:
URL: https://github.com/apache/solr/pull/250#discussion_r799289796
##########
File path: solr/bin/solr
##########
@@ -884,8 +887,12 @@ function stop_solr() {
sleep 10
fi
- CHECK_PID=`ps auxww | awk '{print $2}' | grep -w $SOLR_PID | sort -r | tr -d ' '`
- if [ "$CHECK_PID" != "" ]; then
+ STAT=`ps -o stat='' $SOLR_PID | tr -d ' '`
+ if [ "$STAT" == "Z" ]; then
+ # This can happen if, for example, you are running Solr inside a docker container with multiple processes
+ # rather than running it is as the only service. The --init flag on docker avoids that particular problem.
+ echo -e "Solr process $SOLR_PID has terminated abnormally. Solr has exited but a zombie process entry remains."
Review comment:
Fair question. I think you're right that it should exit 1, since something is wrong.
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[GitHub] [solr] colvinco commented on pull request #250: SOLR-15558: Identify zombie processes when stopping
Posted by GitBox <gi...@apache.org>.
colvinco commented on pull request #250:
URL: https://github.com/apache/solr/pull/250#issuecomment-1026658180
@madrob - could you possibly review this?
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[GitHub] [solr] colvinco commented on pull request #250: SOLR-15558: Identify zombie processes when stopping
Posted by GitBox <gi...@apache.org>.
colvinco commented on pull request #250:
URL: https://github.com/apache/solr/pull/250#issuecomment-1029795985
Thank you, changes made
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[GitHub] [solr] madrob commented on a change in pull request #250: SOLR-15558: Identify zombie processes when stopping
Posted by GitBox <gi...@apache.org>.
madrob commented on a change in pull request #250:
URL: https://github.com/apache/solr/pull/250#discussion_r798964034
##########
File path: solr/bin/solr
##########
@@ -884,8 +887,12 @@ function stop_solr() {
sleep 10
fi
- CHECK_PID=`ps auxww | awk '{print $2}' | grep -w $SOLR_PID | sort -r | tr -d ' '`
- if [ "$CHECK_PID" != "" ]; then
+ STAT=`ps -o stat='' $SOLR_PID | tr -d ' '`
+ if [ "$STAT" == "Z" ]; then
+ # This can happen if, for example, you are running Solr inside a docker container with multiple processes
+ # rather than running it is as the only service. The --init flag on docker avoids that particular problem.
+ echo -e "Solr process $SOLR_PID has terminated abnormally. Solr has exited but a zombie process entry remains."
Review comment:
Is this considered an error condition? I'm not sure. Maybe worthwhile to `exit 1` still? I'm not sure what your code calling this script would expect.
##########
File path: solr/bin/solr
##########
@@ -842,34 +842,37 @@ function stop_solr() {
STOP_KEY="$3"
SOLR_PID="$4"
- if [ "$SOLR_PID" != "" ]; then
- echo -e "Sending stop command to Solr running on port $SOLR_PORT ... waiting up to $SOLR_STOP_WAIT seconds to allow Jetty process $SOLR_PID to stop gracefully."
- "$JAVA" $SOLR_SSL_OPTS $AUTHC_OPTS -jar "$DIR/start.jar" "STOP.PORT=$THIS_STOP_PORT" "STOP.KEY=$STOP_KEY" --stop || true
- (loops=0
- while true
- do
- CHECK_PID=`ps auxww | awk '{print $2}' | grep -w $SOLR_PID | sort -r | tr -d ' '`
- if [ "$CHECK_PID" != "" ]; then
- slept=$((loops * 2))
- if [ $slept -lt $SOLR_STOP_WAIT ]; then
- sleep 2
- loops=$[$loops+1]
- else
- exit # subshell!
- fi
- else
- exit # subshell!
- fi
- done) &
- spinner $!
- rm -f "$SOLR_PID_DIR/solr-$SOLR_PORT.pid"
- else
+ if [ -z "$SOLR_PID" ]; then
Review comment:
nit: can we change this test to `-n` so that we minimize the diff a little bit? Makes it easier to review.
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[GitHub] [solr] janhoy commented on pull request #250: SOLR-15558: Identify zombie processes when stopping
Posted by GitBox <gi...@apache.org>.
janhoy commented on pull request #250:
URL: https://github.com/apache/solr/pull/250#issuecomment-1030139879
Have you run the entire test suite, including `TestSolrCLIRunExample`, which seems to start the example using the bin/solr script and then stop it again...
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[GitHub] [solr] madrob closed pull request #250: SOLR-15558: Identify zombie processes when stopping
Posted by GitBox <gi...@apache.org>.
madrob closed pull request #250:
URL: https://github.com/apache/solr/pull/250
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