Default queue is too small for `SingleAttestation` messages post-Pectra

[michaelsproul]

Since the Pectra fork on mainnet some nodes are logging messages like:

ERROR Unable to queue converted SingleAttestation error: no available capacity, slot: 4230400

This is because each attestation now generates two events that are plumbed through the beacon processor: one for converting SingleAttestation to Attestation, and one for processing that Attestation.

Workaround

Users seeing this error can increase the size of the queue using the hidden flag:

--beacon-processor-work-queue-len 65536

There isn't really an upper bound for how many events this queue might need to hold, so this increase is somewhat arbitrary (it is highly hardware dependent). Users can safely continue increasing the bound until they reach an acceptable frequency of queue-full events on their hardware.

The Proper Fix

The number of events will be reduced back to pre-Pectra levels once this issue is closed:

• Optimise SingleAttestation implementation further #6970

There is an open PR against unstable that is awaiting review:

• Single attestation "Full" implementation #7444

Once that is ready, we can release it as part of v7.1.0.