Spring Boot + Cloud Foundry Heap Dump Examples

References

https://community.pivotal.io/s/article/how-to-generate-and-download-java-application-heap-dump-from-cloud-foundry-container?language=en_US

Methods

OOM Heapdumps with the Java Kill Agent

To begin, ensure your app will be bound to a volume service with the string heap-dump in its name or tag. Terminal heap dumps will be written to it with the pattern:

<CONTAINER_DIR>/<SPACE_NAME>-<SPACE_ID[0,8]>/<APPLICATION_NAME>-<APPLICATION_ID[0,8]>/<INSTANCE_INDEX>-<TIMESTAMP>-<INSTANCE_ID[0,8]>.hprof

Service binding example (this is also taken care of in manifest.yml):

cf bind-service jbp-oom-example heap-dump -c '{"mount":"/var/heap-dump"}'

You should see the following logged on startup:

Write terminal heap dumps to /var/heap-dump/playground-9d67e169/jbp-oom-example-7728eab2/$CF_INSTANCE_INDEX-%FT%T%z-${CF_INSTANCE_GUID:0:8}.hprof

Next, trigger an OOM conditon by POSTing to the /oom endpoint:

curl -X POST https://jbp-oom-example.yourdomain.com/oom

You should see the following in the logs indicating a heapdump was captured:

2020-06-16T14:16:21.11-0500 [APP/PROC/WEB/0] OUT Heapdump written to "/var/heap-dump/playground-9d67e169/jbp-oom-example-7728eab2/0-2020-06-16T19:16:20-0000-ecf6826b.hprof"
...
...
2020-06-16T14:16:21.12-0500 [APP/PROC/WEB/0] ERR jvmkill killing current process

Ad-Hoc Heapdumps with Spring Boot Actuator

The easiest option is to use Spring Boot Actuators. For Spring Boot apps with actuators enabled, a heap dump is available at the /actuator/heapdump endpoint in Spring Boot 2.x. Please refer details at Spring Boot v2.1.x.RELEASE - Part V. Spring Boot Actuator: Production-ready features.

Enable Spring Boot Actuator

In build.gradle add the spring-boot-starter-actuator dependency:

dependencies {
    implementation 'org.springframework.boot:spring-boot-starter-actuator'
    ...
}

Enable the /actuator/heapdump Endpoint

In application.yml, add the following:

management:
  endpoints:
    web:
      exposure:
        include: health,info,heapdump
  endpoint:
    heapdump:
      enabled: true

Obtain the Heap Dump

You can either navigate to the /actuator/heapdump endpoint in a browser to download or output it via curl. For example:

curl 'http://localhost:8080/actuator/heapdump' -O

Building

./gradlew assemble