27 September 2011

SRM speedup update

Or should that be speedupdate? If you remember the Jamboree last year, in Amsterdam, one of the suggestions to decrease the negotiation overheads in SRM by making more efficient use of the socket. Our very own Paul Millar from DESY has come up with a demonstrator using a lua shell which is able to reach SRMs by calling the functions in the API, like S2 does, but with perhaps a simpler language to learn, and you're in a shell.

What Paul demonstrated was the speedup associated with calling each function individually, and then by turning off GSI delegation, and finally by reusing the socket using HTTP KeepAlive. You'd not be surprised to see a big improvement - but of course the server must support KeepAlive.

Combined with the immediate return on srmGet when a file does not need staging, this could again speed up multiple file accesses (and of course you can still submit multiple file requests in a single SRM request.)

Paul has published the code, you can find the dCache LUA SRM interface.on the dCache web site.

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