chain head listener: Reduce locking #2763
Merged
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In hosted a subgraph was observed to hang in
new_block_stream
, which could mean hanging inChainHeadListener::subscribe
, so this lock might be involved. This switches the Mutex to an RwLock which will only see write locks when the networks are first inserted, so it practically removes contention. This should at least reduce the impact of a task hanging while holding the lock. The implementation is basically what it was before #2366, but being mindful of race conditions.