[GitHub] [trafficserver] shinrich commented on a change in pull request #6978: Add option for hybrid global and thread session pools

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shinrich commented on a change in pull request #6978:
URL: https://github.com/apache/trafficserver/pull/6978#discussion_r463046907



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File path: doc/admin-guide/files/records.config.en.rst
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@@ -990,6 +990,22 @@ mptcp
    ``thread`` Re-use sessions from a per-thread pool.
    ========== =================================================================
 
+.. ts:cv:: CONFIG proxy.config.http.server_session_sharing.pool_hybrid_limit INT 0
+
+   Setting :ts:cv:`proxy.config.http.server_session_sharing.pool` to global can reduce
+   the number of connections to origin for some traffic loads.  However, if many
+   execute threads are active, the thread contention on the global pool can reduce the
+   lifetime of connections to origin and reduce effective origin connection reuse. The
+   :ts:cv:`proxy.config.http.server_session_sharing.pool_hybrid_limit` setting lets you
+   enable a hybrid pool mode using both global and per thread pools.  If hybrid mode
+   is enabled, sessons are returned to the local thread pool if the global pool lock is
+   not acquired rather than just closing the origin connection as is the case in standard
+   global mode.
+
+   Setting it to 0, disables hybrid mode.  Setting it to -1, enables hybrid

Review comment:
       Yes, as it stands, it is using hybrid limit as a modifier to the pool setting.  As I noted below, it isn't clear to me from my testing so far that you gain anything by messing with the limit beyond turning it all the way on (-1) or off (0).  In that case, I agree that just making a hybrid pool option would be a clearer config.
   
   I guess I could keep around the hybrid_limit has a lesser used tuning option that is set to -1 by default but only used if pool == hybrid. 




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