-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 Mark,
On 11/7/13, 4:44 PM, Mark Thomas wrote: > On 07/11/2013 21:10, Christopher Schultz wrote: > >> Can you describe the effective difference between my >> over-simplified description and what is implemented in >> commons-pool (ignoring thread-fairness, which I'll admit is a >> very useful feature)? > > For starters, the relatively expensive validation process is > outside the sync. Given where this thread started, that is a key > point. > > Object creation, destruction, activation and deactivation are also > all outside the syncs. Creation and destruction are very likely to > be expensive as well (else why bother with a pool). > > The key difference is that pool uses syncs to give a thread > permission to create an object, borrow an object, etc. Giving > permission is very quick. The actual action is taken outside of the > syncs as that is slow and expensive. > > You will still hit a synchronisation bottleneck with very high > concurrency but I have a hard time believing most real world apps > would actually get anywhere near the concurrency levels you need > to reach to hit this bottleneck - if you use a recent version of > Pool and DBCP. Agreed. Presumably, a Connection is being checked-out of the pool in order to ... make some JDBC calls. Those are going to be way slower than any of this synchronization we're discussing. But, pathologically-speaking, a couple of hundred threads doing nothing but repeatedly borrowing and returning JDBC connections are going to expose a "horrible synchronization nightmare" in the implementation. But that will be the case no matter what the implementation, given the whole point of an object-pool. > jdbc-pool and Pool2+DBCP2 remove the bottleneck entirely so in the > unliekly event you have an app with that much concurrency, a > bottleneck in the connection pool won't be an issue. I'll have to look at how both of those libraries actually work under the covers. I've never bothered to look... - -chris -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.15 (Darwin) Comment: GPGTools - http://gpgtools.org Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQIcBAEBCAAGBQJSfAxoAAoJEBzwKT+lPKRYVAIP/j72A6/+AHi89bG53rdBlvCI wK550RM3udBt09lbhGZBWCe6qaj9sQdsgsp7MHO+ebj6/bx5bKdDQ+Pt4F28yUf7 ku3dubNjInTAB3xn25jY8MBPkzz82+8RrAsTc8QD0r/m/njsuRlM6EAu617GcI0q PmAXlSLUmTAhSVAbPQ+ZqqdXA/eM8hu/NgT6ZyBIo/yez/jBrIzyGdHIGHKXsqRp 0N0ANH22o0uqgYms8tYpQgv1M/PJHLe9Br6e9aNPTJC9b3FZfq+fD/gbripGEnHC GGqmT5+Pk3+n9bbPpp5JPJ1oDZY33SYE8CihJ7NBRrD14Egd3oqbotG8/LWmgDjk lil/4Z0PuVpHPXzz3N+H5FGw83eJ4T8+vJs3EIxw4HrOSvwzyypmMFM6Z/UCmSbT wCO4C47m84Omi3UX9r2ha9Wk7/oVh5O1g4nteHU1MJEO/BaiR7M/Q1BHAeKC4LSF 0zHwUVvgJzMHtCQBbaPYq2LynXiLk+RdWsIaC1ZBLAuBUVSThpv6NHau5xeKKHsx gop897wXf3+t08js0JrfCRYq5ZglY2bO7DFXU6RFLwrRwVBGH6AV98us9a38nb8h 8XhK0GORm4p5QMRk2CBOOp0sKcSbihEhV3KHX4JymdnSvtdGXYMZuscBcpiwbMuV nHZq/nfhfYXpIKKsPvMx =8N8d -----END PGP SIGNATURE----- --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
