Detecting concurrency issues with JCStress

Java is a very popular programming language with a consistent set of multithreading and multiprocessing features, which solve all kinds of modern enterprise problems and enable memory sharing across threads as part of the Java concurrency model.

Developers use popular frameworks like Spring, Quarkus, Micronaut, Akka or Spark every day. In some scenarios, it is necessary to use concurrency, although in reality the learning curve is not easy and sometimes software gets deployed to cloud environments with some hidden concurrency bugs.

The talk will review the root causes of concurrency issues, and give an introduction into the Java tool JCStress by explaining how to create tests for Java classes with shared states.

• https://www.meetup.com/nl-NL/amsterdam-java-user-group/events/287658432/

Running the example locally:

sdk env
./gradlew clean build jcstress
./gradlew clean jcstress --tests "Calculator4Test"
./gradlew clean build
./gradlew clean bootRun

http://localhost:8080/swagger-ui/index.html
http://localhost:8080/v3/api-docs
https://editor.swagger.io/

Running Visualvm, Jmeter & Taurus to add load:

sdk install visualvm
visualvm --jdkhome  $JAVA_HOME

java -Xms256m -Xmx256m -XX:+UseParallelGC -jar build/libs/101-concurrency-0.1.0-SNAPSHOT.jar
sdk install jmeter
jmeter -t jmeterConf.jmx
jmeter -t jmeterConf.jmx -n
jmeter -t jmeterConf2.jmx

brew install python
python3 --version
pip3 install bzt
bzt taurusConf.yaml

Running JCStress examples:

./gradlew clean jcstress --tests "API_01_Simple"
./gradlew clean jcstress --tests "API_02_Arbiters"
./gradlew clean jcstress --tests "API_04_Nesting"
./gradlew clean jcstress --tests "API_05_SharedMetadata"
./gradlew clean jcstress --tests "API_06_Descriptions"

sdk env
jwebserver -p 8000 -d  $PWD/docs

• https://docs.oracle.com/javase/specs/jls/se8/html/jls-17.html
• https://download.oracle.com/otndocs/jcp/memory_model-1.0-pfd-spec-oth-JSpec/
• https://gee.cs.oswego.edu/dl/jmm/cookbook.html
• https://github.com/openjdk/jcstress
• https://github.com/reyerizo/jcstress-gradle-plugin
• https://shipilev.net/talks/hydraconf-June2021-jcstress-workshop.pdf
• https://shipilev.net/blog/2016/close-encounters-of-jmm-kind/
• https://shipilev.net/blog/2014/safe-public-construction/
• https://shipilev.net/blog/2014/jmm-pragmatics/
• https://shipilev.net/jvm/anatomy-quarks/jvm-anatomy-quarks-complete.pdf
• https://jenkov.com/tutorials/java-concurrency/java-memory-model.html