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new 94d3355b78f MINOR: Fix zombie process issue in ducker containers by
using `--init` (#20899)
94d3355b78f is described below
commit 94d3355b78fd76f5267351be8d225851d4845f11
Author: Ken Huang <[email protected]>
AuthorDate: Thu Nov 20 14:43:12 2025 +0800
MINOR: Fix zombie process issue in ducker containers by using `--init`
(#20899)
While running Kafka e2e tests, various tests were failing with
`TimeoutError('Kafka node failed to stop in 60 seconds')`. In Kafka e2e
tests, we check the PID to ensure the Kafka server has shut down. After
investigating this issue, I found that the Kafka process was a zombie
process in the container:
```bash
ducker@ducker05:/$ jcmd
285 kafka.Kafka /mnt/kafka/kafka.properties
18207 jdk.jcmd/sun.tools.jcmd.JCmd
ducker@ducker05:/$ cat /proc/285/status | grep -i state
State: Z (zombie)
```
This issue is related to [this
change](https://github.com/apache/kafka/pull/17554/files#r1845737954).
When using `CMD ["sudo", "service", "ssh", "start", "-D"]`, PID 1
becomes the SSH service, which does not handle `SIGCHLD` signals and
therefore won't reap zombie processes:
```bash
ducker@ducker05:/$ cat /proc/1/cmdline | tr '\0' ' '
sudo service ssh start -D
```
However, with the old syntax `CMD sudo service ssh start && tail -f
/dev/null`, PID 1 is `/bin/sh`, which is a shell that properly reaps
zombie processes:
```bash
ducker@ducker05:/$ cat /proc/1/cmdline | tr '\0' ' '
/bin/sh -c sudo service ssh start && tail -f /dev/null
```
Use `tini` as PID 1 to properly manage processes and avoid zombie
processes from remaining in the system.
Reviewers: PoAn Yang <[email protected]>, TaiJuWu <[email protected]>,
Chia-Ping Tsai <[email protected]>
---
tests/docker/ducker-ak | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/tests/docker/ducker-ak b/tests/docker/ducker-ak
index 7947165376e..54bf1dfb95d 100755
--- a/tests/docker/ducker-ak
+++ b/tests/docker/ducker-ak
@@ -45,7 +45,7 @@ docker_run_memory_limit="2000m"
default_num_nodes=14
# The default JDK base image with apt-get support.
-# The openjdk image has been officially deprecated. For more imformation, see:
https://hub.docker.com/_/openjdk
+# The openjdk image has been officially deprecated. For more information, see:
https://hub.docker.com/_/openjdk
default_jdk="sapmachine:17-jdk-ubuntu-jammy"
# The default ducker-ak image name.
@@ -95,18 +95,18 @@ up [-n|--num-nodes NUM_NODES] [-f|--force] [docker-image]
the ducker container. Defaults to ${default_jdk}. Example: -j
openjdk:17-bullseye
If --ipv6 is specified, we will create a Docker network with IPv6 enabled.
-
- Note that port 5678 will be automatically exposed for ducker01 node and
will be mapped to 5678
+
+ Note that port 5678 will be automatically exposed for ducker01 node and
will be mapped to 5678
on your local machine to enable debugging in VS Code.
test [-d|--debug] [test-name(s)] [-- [ducktape args]]
Run a test or set of tests inside the currently active Ducker nodes.
For example, to run the system test produce_bench_test, you would run:
./tests/docker/ducker-ak test
./tests/kafkatest/tests/core/produce_bench_test.py
-
+
If --debug is passed, the tests will wait for remote VS Code debugger to
connect on port 5678:
./tests/docker/ducker-ak test --debug
./tests/kafkatest/tests/core/produce_bench_test.py
-
+
To pass arguments to underlying ducktape invocation, pass them after `--`,
e.g.:
./tests/docker/ducker-ak test
./tests/kafkatest/tests/core/produce_bench_test.py -- --test-runner-timeout
1800000
@@ -337,7 +337,7 @@ docker_run() {
# container to fix permission issues with mounted volumes
podman_userns_option="--userns=keep-id"
fi
- must_do -v ${container_runtime} run --privileged \
+ must_do -v ${container_runtime} run --init --privileged \
-d -t -h "${node}" --network ducknet "${expose_ports}" \
--memory=${docker_run_memory_limit} ${memory_swappiness_option}
${podman_userns_option} \
-v "${kafka_dir}:/opt/kafka-dev" --name "${node}" -- "${image_name}"
@@ -580,7 +580,7 @@ ducker_test() {
esac
done
local ducktape_args=${*}
-
+
[[ ${#test_name_args} -lt 1 ]] && \
die "ducker_test: you must supply at least one system test to run.
Type --help for help."
local test_names=""
@@ -594,7 +594,7 @@ ducker_test() {
test_names="${test_names} ${test_name}"
fi
done
-
+
must_pushd "${kafka_dir}"
( (test -f ./gradlew || gradle) && ./gradlew systemTestLibs ) || die
"ducker_test: Failed to build system test libraries, please check the error
log."
must_popd
