Do not quite get it.
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It is because neither can proceed. They’re waiting on a lock held by the other, and neither will release its lock until it finishes. 2PL won’t help for the problem is in the waiting and not the locking.
just wait. i mean
In 2PL, a deadlock happens when transactions hold locks and wait on each other in a circular chain.
In this case, T1 acquires a lock on resource A and requests B, while T2 already holds B and requests A. Since 2PL does not allow releasing locks before all required locks are acquired (during the growing phase), neither transaction can proceed.
So both transactions are waiting indefinitely:
T1 → waiting for B (held by T2)
T2 → waiting for A (held by T1)
This circular wait condition is exactly what creates a deadlock under Two-Phase Locking.
-Prestige Safety Nets
