For IBM Java
WSVR0605W: Thread threadname has been active for hangtime and may be hung.There are total threads threads in total in the server that may be hung. ```
where threadname is the name displayed in the JVM thread dump, hangtime is the approximate elapsed time since the thread was active, and totalthreads is the overall rating of system threads.
IBM Heap Analyzer
IBM Thread and Monitor Dump Analyzer for Java (TMDA)
IBM Pattern Modeling and Analysis Tool for Java Garbage Collector (PMAT)
Check with GC timing + standard output etc.