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Virtual mode uses advisory locks with TTL to prevent concurrent operations from conflicting. Locks are stored in the state database and are scoped to specific resources.

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Lock types

Different VDEs can be locked concurrently. Two builds targeting different VDEs do not block each other.

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Lock behavior

  • Locks have an expiry time (expires_at). Active locks are those where expires_at > now.
  • When a lock is successfully released, the lock row is deleted.
  • Acquiring a lock over an expired lock replaces it.
  • Owner identity is checked on release - only the owner that acquired the lock can release it.

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When locks block

If a lock is active and an operation requires it, the operation fails immediately with a clear error:
The operation does not wait or retry. This is intentional - SQLBuild does not implement lock queuing. If a lock is active, either wait for the holding operation to complete or clear the lock manually.

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Inspecting locks

List active locks:

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Clearing stuck locks

If a process crashed while holding a lock, the lock may remain active until it expires. To clear it immediately:
Only clear locks when you are certain the holding operation is no longer running. Clearing a lock while the operation is still active can cause state corruption.

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Lock expiry

Locks are acquired with a TTL (typically 10 minutes for VDE locks). If an operation takes longer than the TTL, the lock expires and another operation can acquire it. This is a safety net against abandoned locks, not a normal operating condition. If operations consistently exceed the lock TTL, the TTL may need to be increased in a future configuration option.