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valayDavevalayDave
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[card-cache] optimizations to avoid deadlocks
- deadlocks happened when cleanups coincided with heavy load - tests simulating a cleanup (disk + shared-objects) and heavy load together were successfully able to reproduce the deadlock situation - Locking at the `context` level: - Each time we want to clean up we lock to create a new context - All directories/processes are written within that new context. - Switching this context which ensure that all new processes get created differently and the cleanup process can safely remove everything. - Context also sets the read/write directory for the cache object used in the API endpoint. - All locking on the API side now always time-bound. The code time's out if it can't acquire a lock. - The method ensure that all operations won't in-definately hold the lock. - Changed defaults for minimum amount to time to wait for cards in the cache process to 20 seconds (helps make things snappier) - Added `timings` dict in card cache to optimize loading cycles (Ensured that it is set based on a per-card basis)
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‎services/ui_backend_service/api/card.py‎

Lines changed: 3 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -153,11 +153,12 @@ async def get_card_content_by_hash(self, request):
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task,
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hash,
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)
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html_reload_script = "<script>window.needsReload = true;</script><body></body>"
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if cards is None:
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return web.Response(
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content_type="text/html",
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status=404,
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body="Card not found for task. Possibly still being processed. Please refresh page to check again.",
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body=html_reload_script,
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)
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if cards and hash in cards:
@@ -275,7 +276,7 @@ async def get_card_data_for_task_async(
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step_name=task.get("step_name"),
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task_id=task.get("task_name") or task.get("task_id"),
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)
278-
await cache_client.cache_manager.register(pathspec)
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await cache_client.cache_manager.register(pathspec, lock_timeout=0.2)
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_local_cache = cache_client.cache_manager.get_local_cache(pathspec, card_hash)
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if not _local_cache.read_ready():
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# Since this is a data update call we can return a 404 and the client

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