Hanganalyze Tracefile-Interpretation

Hi Guys,

Can someone please help me understand from the hanganalyze level 3 tracefile.Like, who is the final blocker.Is it the final blocker in chain 1?

Chains most likely to have caused the hang:

[a] Chain 1 Signature: <not in a wait><='library cache lock'<='library cache lock'<='cursor: pin S wait on X'

     Chain 1 Signature Hash: 0x12f5c63d

[b] Chain 2 Signature: 'rdbms ipc message'<='library cache lock'

     Chain 2 Signature Hash: 0x6a8de15c

[c] Chain 3 Signature: 'PX Deq: Execution Msg'<='PX Deq: Parse Reply'

     Chain 3 Signature Hash: 0x29c5ca9b

Thanks