Intelligent SMT thread hang detect taking into account shared resource contention/blocking

Monitoring is performed to detect a hang condition. A timer is set to detect a hang based on a core hang limit. If a thread hangs for the duration of the core hang limit, then a core hang is detected. If the thread is performing an external memory transaction, then the timer is increased to a longer memory hang limit. If the thread is waiting for a shared resource, then the timer may be increased to the longer memory hang limit if another thread or, more particularly, the thread blocking the resource has a pending memory transaction. Responsive to detecting a hang condition, instructions dispatched to the plurality of execution units may be flushed, or the processor may be reset and restored to a previously known good, checkpointed architected state.