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https://issues.apache.org/jira/browse/TS-4331?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15315597#comment-15315597
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ASF GitHub Bot commented on TS-4331:
------------------------------------
Github user jacksontj commented on a diff in the pull request:
https://github.com/apache/trafficserver/pull/653#discussion_r65805818
--- Diff: iocore/hostdb/P_RefCountCache.h ---
@@ -281,6 +311,14 @@
RefCountCachePartition<C>::copy(std::vector<RefCountCacheHashingValue> *items)
}
}
+template <class C>
+void
+RefCountCachePartition<C>::metric_inc(int metric_enum, int64_t data) {
+ if (this->rsb) {
+ RecIncrGlobalRawStatCount(this->rsb, metric_enum, data);
--- End diff --
Maybe? Whats there now works (meaning the numbers are correct). When I
switch to that the metrics seems all messed up, presumably because they are of
type `RecRawStatSyncCount` -- is there just a RecRawStatSync (not that exact
name, I looked-- can't find the equivalent).
> Hostdb consistency problems due to MultiCache
> ---------------------------------------------
>
> Key: TS-4331
> URL: https://issues.apache.org/jira/browse/TS-4331
> Project: Traffic Server
> Issue Type: Bug
> Components: HostDB
> Reporter: Thomas Jackson
> Assignee: Thomas Jackson
> Fix For: 7.0.0
>
>
> This ticket is for the correct long term fix to TS-4207
> pulled from a comment, which wraps up the issue
> {quote}
> Leif Hedstrom I have spent a decent amount of time on this while I was OOO on
> vacation the last couple of weeks. It seems that the root cause of this issue
> has always existed, and that the addition of always doing hostname storing
> (https://github.com/apache/trafficserver/commit/0e703e1e) we are just causing
> the issue to happen all the time.
> To understand the issue I'll give a little background in how hostdb is
> currently working. Basically hostdb is just a wrapper around this templated
> struct called MultiCache. MultiCache is "multi" not because it is templated,
> but because it has two types of storage (static-- blocks and dynamic--
> alloc). The static side of the cache can hold N HostDBInfo structs (the
> results of DNS queries). The dynamic side is used to store the round robin
> records and various strings associated with the record. The size of this
> dynamic space is defined as (N x [estimated_heap_bytes_per_entry. The basic
> problem we are running into is that we are putting too much preassure on the
> dynamic heap-- such that the heap is getting re-used while people still have
> references to items in that space.
> So, I've actually been working on re-writing MultiCache to allocate the
> entire required block at once (so we don't have this problem where the parent
> exists but not the children), but I'm not certain if we want such a change to
> go into the 6.x branch (I'm willing to discuss if we want). If we aren't
> comfortable with such a large change I suggest just accounting for the
> hostname size in the estimated_heap_bytes_per_entry as a stopgap solution.
> The maximum allowable size is 253 (so 254 with null terminator), but we could
> pick a smaller number (~120 or so seems to be more reasonable). Alternatively
> you can increase the number of records in hostdb (and the size accordingly)
> to increase the dynamic heap size.
> TLDR; almost done with the long term solution, but I'm not sure if we want to
> merge that into 6.x-- alternatively we can do a simple workaround in 6.x
> (https://github.com/apache/trafficserver/pull/553)
> {quote}
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