Virtual Threads

Virtual threads are lightweight threads finalized in JDK 21. The introduction of virtual threads allows programs to use a larger number of threads than the amount of threads made available by the underlying OS.

A virtual thread only consumes an OS thread while performing calculations on the CPU, the OS thread is freed when performing a blocking I/O operation. This allows for an increased throughput as other virtual threads can execute while some are waiting due to I/O operations.

Virtual threads are generally not recommended for CPU-intensive tasks.

From JobRunr 7 and later, worker threads are by default virtual threads when the JDK version is 21 or later (virtual threads are only available when JDK is version 21 or later).

Configuration

JobRunr allows to define worker threads as PlatformThreads or VirtualThreads. Below are different ways to configure JobRunr to use either of those type of threads - just choose your preferred thread type depending on your expected workload:

org.jobrunr.background-job-server.thread-type=PlatformThreads
#or org.jobrunr.background-job-server.thread-type=VirtualThreads