How did you detect deadlock situations in systems?

Methods commonly used to detect deadlocks in systems include:

• Log analysis and thread tracing: studying logs and thread states to identify which resources are held and which threads are waiting for them.

• Using profiling and monitoring tools: for example, in Java, jstack can be used to obtain thread dumps, showing which threads are blocked and on which objects.

• Visualization of lock graphs: constructing a resource acquisition and wait graph to detect cycles, which are the cause of deadlocks.

• Testing with resource acquisition order control: checking code for potential cyclic dependencies.

Example of using jstack:

jstack <pid> > threaddump.txt

In the dump, look for lines with BLOCKED and analyze which objects are causing the lock.