zhouyifan279 commented on code in PR #41105:
URL: https://github.com/apache/spark/pull/41105#discussion_r1191865529
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core/src/main/scala/org/apache/spark/deploy/history/ApplicationCache.scala:
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@@ -48,11 +48,28 @@ private[history] class ApplicationCache(
val retainedApplications: Int,
val clock: Clock) extends Logging {
+ /**
+ * Keep track of SparkUIs in [[ApplicationCache#appCache]] and SparkUIs
removed from
+ * [[ApplicationCache#appCache]] but not detached yet.
+ */
+ private val loadedApps = new ConcurrentHashMap[CacheKey, CountDownLatch]()
+
private val appLoader = new CacheLoader[CacheKey, CacheEntry] {
/** the cache key doesn't match a cached entry, or the entry is
out-of-date, so load it. */
override def load(key: CacheKey): CacheEntry = {
- loadApplicationEntry(key.appId, key.attemptId)
+ // Ensure old SparkUI has been detached before loading new one.
+ val removalLatch = loadedApps.get(key)
+ if (removalLatch != null) {
+ // Old SparkUI is in the middle of detaching.
+ // Waiting 10 seconds should be enough since detaching usually takes
less than 1 second.
+ if (!removalLatch.await(10, TimeUnit.SECONDS)) {
Review Comment:
> removal essentially can be held up by a few synchronized blocks
Can you provide an example? From what I know, removal are mostly triggered
by `ApplicationCache#withSparkUI`, which only causes http requests to the same
<appId, attemptId> being blocked.
> do we have any stats on how long this takes ? How did we end up with < 1 s
estimate ?
There is no heavy operation in the code path of
`ApplicationCache#removalListener#onRemoval`.
The most heavy operation is deleting app data directory on disk.
I created 10,000 files in a directory and use `rm -rf` to delete it.
Deletion takes 0.339s.
So I think 1 seconds should be enough.
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