Jeff, this is somewhat off topic, but interesting. Are "telehouse" and AWS physically close? Was this latency increase not expected due to geography?
Alexander On 28 November 2012 06:21, Neil Davies <semanticphilosop...@gmail.com>wrote: > Jeff > > Are you certain that all the delay can be laid at the GHC runtime? > > How much of the end-to-end delay budget is being allocated to you? I > recently moved a static website from a 10-year old server in telehouse into > AWS in Ireland and watched the access time (HTTP GET to check time on top > index page) increase by 150ms. > > Neil > > On 27 Nov 2012, at 19:02, Jeff Shaw <shawj...@gmail.com> wrote: > > > Hello Timothy and others, > > One of my clients hosts their HTTP clients in an Amazon cloud, so even > when they turn on persistent HTTP connections, they use many connections. > Usually they only end up sending one HTTP request per TCP connection. My > specific problem is that they want a response in 120 ms or so, and at times > they are unable to complete a TCP connection in that amount of time. I'm > looking at on the order of 100 TCP connections per second, and on the order > of 1000 HTTP requests per second (other clients do benefit from persistent > HTTP connections). > > > > Once each minute, a thread of my program updates a global state, stored > in an IORef, and updated with atomicModifyIORef', based on query results > via HDBC-obdc. The query results are strict, and atomicModifyIORef' should > receive the updated state already evaluated. I reduced the amount of time > that query took from tens of seconds to just a couple, and for some reason > that reduced the proportion of TCP timeouts drastically. The approximate > before and after TCP timeout proportions are 15% and 5%. I'm not sure why > this reduction in timeouts resulted from the query time improving, but this > discovery has me on the task of removing all database code from the main > program and into a cron job. My best guess is that HDBC-odbc somehow > disrupts other communications while it waits for the DB server to respond. > > > > To respond to Ertugrul, I'm compiling with -threaded, and running with > +RTS -N. > > > > I hope this helps describe my problem. I c an probably come up with some > hard information if requested, E.G. threadscope. > > > > Jeff > > > > On 11/27/2012 10:55 AM, timothyho...@seznam.cz wrote: > >> Could you give us more info on what your constraints are? Is it > necessary that you have a certain number of connections per second, or is > it necessary that the connection results very quickly after some other > message is received? > > > > > > _______________________________________________ > > Haskell-Cafe mailing list > > Haskell-Cafe@haskell.org > > http://www.haskell.org/mailman/listinfo/haskell-cafe > > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe >
_______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
