I'm interested in using distcc in a group of 16 programmers where all 16 workstations are equally fast, all 16 workstations are both compile servers and compile clients, and all access a shared copy of distcc over NFS or SMB. Several potential problems come to mind when thinking about this:
1. Since the list of hosts read from $prefix/etc/distcc/hosts is the same for all workstations, every workstation will issue large compile jobs to itself sometimes even though it'd be better off only handling preprocessing and linking (right?)
We couldn't demonstrate this with our little synthetic benchmark. (Maybe it happens in the real world; no idea.)
2. Distcc won't currently check the load average of each compile server, so workstations busy with non-distcc jobs will get slammed with distcc jobs, negatively impacting normal use of the workstations.
3. If more than one user is issuing distcc jobs, their distcc's
will sometimes issue jobs to the same machine by chance
(fairly often, if distcc assigns jobs in order of the etc/distcc/hosts file).
We did verify these two just now using a trivial synthetic benchmark.
It'd probably be 'easy' to make the distcc server check the load average, and drop the connection if it was over some configurable threshold. As dparent.c says,
* @todo Quite soon we need load management. Basically when we think * we're "too busy" we should stop accepting connections. This could * be because of the load average, or because too many jobs are * running, or perhaps just because of a signal from the administrator * of this machine.
So maybe we'll try to implement this todo note. - Dan
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