* pq: avoid blocking writer when queue is precisely full
A PQ is considered full (and therefore needs to block before releasing the
writer) when its persisted size on disk _exceeds_ its `queue.max_bytes`
capacity.
This removes an edge-case preemptive block when the persisted size after
writing an event _meets_ its `queue.max_bytes` precisely AND its current
head page has insufficient room to also accept a hypothetical future event.
Fixes: elastic/logstash#16172
* docs: PQ `queue.max_bytes` cannot be less than `queue.page_capacity`
* Logstash checks different file system if each pipeline has a symlink to other filesystem.
* Apply suggestions from code review
* FileAlreadyExistsException case handling when queue path is symlinked.
Co-authored-by: Karen Metts <35154725+karenzone@users.noreply.github.com>
Co-authored-by: Ry Biesemeyer <yaauie@users.noreply.github.com>
Co-authored-by: João Duarte <jsvd@users.noreply.github.com>
a 50ms delay helps creating more full batches without practical added latency see #8707
a 64mb page helps PQ perfmance related to a large page size see #8702#8707
* Removed reference to unused `queue.checkpoint.interval`.
* Changed 'unread' to be 'unACKed'
* Remove confusing/contradictory statement about queue acknowledgement
and outputs
* Describe garbage collection
* Describe some of the internals (pages, checkpoints).
Fixes#6408
