Response Time of Wiremock degrades with increase in Load and with increase in mapping Files during Load Testing

[Rakesh Tripathy]

Hi,

We have prepared the mock mappings using wiremock for Load Testing, however we are facing issue of slow Response from wiremock during Load Test.

Currently we have below things in place:-

> We have recorded the Transactions and our Request/Response pairs are in mappings Folder.

> Please note that we have around ~1000 mapping files as we have a lot of flow to cover in Lod Test, however right now we see slow response from wiremock (~1 seconds of response Time) even with just 40 mapping files

> We are using wiremock latest standalone version of Jar and running the jar as standalone java process in a separate server - https://repo1.maven.org/maven2/com/github/tomakehurst/wiremock-jre8-standalone/2.27.2/wiremock-jre8-standalone-2.27.2.jar

> We tried tuning the jvm arguments and also wiremock parameters and finally right now we are using below to bring up wiremcok:-

java -Xms512m -Xmx2048m -XX:+UseParallelOldGC -XX:MaxMetaspaceSize=1024m -Dcom.sun.management.jmxremote.port=9001 -Dcom.sun.management.jmxremote.authenticate=false -Dcom.sun.management.jmxremote.ssl=false -jar /apps/wiremock/wiremock-jre8-standalone-2.27.2.jar --container-threads=500 --async-response-enabled=true --async-response-threads=200 --no-request-journal --disable-request-logging --port 8082 &

We need some help to resolve this slowness issue of Wiremock with load and with more number of mappings.

[Tom Akehurst]

How much CPU and RAM does the machine (or container) running WireMock have?

If you've only got 1 or 2 CPU cores allocated then your thread counts are quite high. I'd suggest going no higher than 100-200 for container threads and 50 for async threads.

Also, worth making sure you've got quite a lot of RAM headroom over the heap + metaspace you've allocated as Jetty uses native byte buffers under the hood which can consume quite a bit of off-heap memory. If this is starting to eat into swap space then it'll slow things down a lot.

TBH, I wouldn't set the GC or metaspace size parameter explicity if you're running on metal or a VM, as the JVM will usually do a better job of tuning these itself. If you're in a container OTOH, sometimes it's worth setting these yourself.