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author | Eelco Dolstra <e.dolstra@tudelft.nl> | 2009-03-23T01·05+0000 |
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committer | Eelco Dolstra <e.dolstra@tudelft.nl> | 2009-03-23T01·05+0000 |
commit | cacff1be886ed975bbef1b17151b25c633711256 (patch) | |
tree | a7e466012a5df86433b7e348c446cf98f9f032c2 /Makefile.am | |
parent | 58969fa2bf9d5e662c372bdf970470b8226bd4c7 (diff) |
* No longer block while waiting for a lock on a store path. Instead
poll for it (i.e. if we can't acquire the lock, then let the main select() loop wait for at most a few seconds and then try again). This improves parallelism: if two nix-store processes are both trying to build a path at the same time, the second one shouldn't block; it should first see if it can build other goals. Also, it prevents the deadlocks that have been occuring in Hydra lately, where a process waits for a lock held by another process that's waiting for a lock held by the first. The downside is that polling isn't really elegant, but POSIX doesn't provide a way to wait for locks in a select() loop. The only solution would be to spawn a thread for each lock to do a blocking fcntl() and then signal the main thread, but that would require pthreads.
Diffstat (limited to 'Makefile.am')
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