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When cloning the gaelyk repository from www.github.com, the performance of the checkout is dramatically bad: pretty much the first file is the jar file found at core\lib\appengine-api-1.0-sdk-1.3.5.jar It is created, but then it grows at a rate of a few dozen bytes per second. This can be reproduced both on Windows and Linux (Ubuntu 10.04 LTS on PC) and is independent of whether the clone is via http or git: http://github.com/glaforge/gaelyk.git git://github.com/glaforge/gaelyk.git There appear huge numbers of Inflater calls.
I diggend into this by adding some debug output. It turns out that DeltaStram.skip() is horribly inefficient. I attach patch files (one in the generic patch format, one in git patch format) which add the debug output. The typical output looks like: Read during 2 skips: 244616 Read outside skips: 512 Read during 3 skips: 489684 Read outside skips: 512 Read during 3 skips: 2415688 Read outside skips: 512 Read during 1 skips: 274937 Read outside skips: 512 Read during 2 skips: 489684 Read outside skips: 512 Read during 2 skips: 2122925 Read outside skips: 512 Read during 2 skips: 450521 Read outside skips: 512 Read during 1 skips: 240251 Read outside skips: 512 (only a very small number of DeltaStream instances shown). The Inflater does around 400 to 500 times more work during skip compared to the actual read work. I didn't quite understand how this happens, but it looks like some weird kind of recursion.
Created attachment 175582 [details] Standard patch format with debug output
Created attachment 175583 [details] Git patch format with debug output
Does http://egit.eclipse.org/r/#change,1441 fix this?
Does not seem to be reproducible anymore. Not sure if http://egit.eclipse.org/r/#change,1441 fixed this (the clone went through without it), but I could clone this repository without problems.
