Bugs item #2891595, was opened at 2009-11-03 17:07
Message generated for change (Tracker Item Submitted) made by csapuntz
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Category: name resolving/DNS
Group: bad behaviour
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Constantine Sapuntzakis (csapuntz)
Assigned to: Daniel Stenberg (bagder)
Summary: DNS cache - outstanding references can prevent timeout

Initial Comment:
Heavy use of a DNS entry by multiple threads can prevent it from being ejected from the cache, even after its timeout has been exceeded. This patch attached fixes this issue.

The patch allows a DNS entry to persist outside of the hash cache and be released when the last connection referencing it calls Curl_resolv_unlock.
It also changes the hash abstraction to replace an entry with a new one by default rather than favoring older entries. I checked the other use of the hash abstraction in multi.c and it already assumes that the insert will either succeed or return NULL -- not that it will return the old element.

I've also added some debugging code that helps catch reference leaks. After curl_easy_cleanup() is called on all extant handles, curl_get_ndns() should return 0.

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Received on 2009-11-04