Install
(For Java11at least version 1.5 is needed) Download Async Profiler from: https://github.com/jvm-profiling-tools/async-profiler
| Code Block |
|---|
wget https://github.com/jvm-profiling-tools/async-profiler/releases/download/v1.7.1/async-profiler-1.7.1-linux-x64.tar.gz mkdir /opt/async-profiler tar xvzf async-profiler-*-linux-x64.tar.gz -C /opt/async-profiler |
Since Kernel 4.6 the following commands must be executed as root on the system to enable profiling
| Code Block |
|---|
echo 1 > /proc/sys/kernel/perf_event_paranoid echo 0 > /proc/sys/kernel/kptr_restrict |
Usage
Find the HiveMQ process id (must be user root or user hivemq)
| Code Block |
|---|
#Java Process ID Tool jps #or #ps with filter for only pid and only processes by user hivemq ps -u hivemq -o pid= #or #always works ps aux | grep hivemq |
Run profiler.sh (-d is the duration of the recording in seconds)
| Code Block |
|---|
/opt/async-profiler/profiler.sh -d 600 -f /(absolute path)/flamegraph.svg <hivemq process id> |
| Info |
|---|
You need to make sure that all async-pofiler files belong to the same user that is running the HiveMQ process and that you start the profiler.sh script as that user. |
Quick command (can be run as root, only works if hivemq is the only process running for user `hivemq`)
| Code Block |
|---|
/opt/async-profiler/profiler.sh -d 600 -f /opt/hivemq/flamegraph.svg `ps -u hivemq -o pid=` |
Kubernetes / Docker
As usual, container platforms have some paranoid settings that are read-only. On the up side, we can leverage the fact that HiveMQ is always PID 1 in containers (unless shared namespaces are used in K8s):
Here's an idempotent block you can simply execute to generate a flamegraph in a container:
| Code Block |
|---|
curl -L https://github.com/jvm-profiling-tools/async-profiler/releases/download/v1.7.1/async-profiler-1.7.1-linux-x64.tar.gz > async.tar.gz tar xfvz async.tar.gz rm -f flame.svg ./profiler.sh -d 60 -f $(pwd)/flame.svg 1 --all-user -e alloc |
Then use kubectl cp or docker cp to copy the graph from the container.
systemd
Alternative: When using systemd, you can simply use
| Code Block |
|---|
systemctl show --property MainPID hivemq | sed -e "s/MainPID=//" |
Using async profiler in the systemd unit (start with HiveMQ):
| Code Block |
|---|
sed -i -e "s|-Djava.net.preferIPv4Stack=true|-Djava.net.preferIPv4Stack=true -agentpath:/opt/async-profiler/build/libasyncProfiler.so=start,svg,file=flamegraph.svg|" /opt/hivemq/bin/run.sh |