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| -rw-r--r-- | doc/todo/avoid_thrashing.mdwn | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/doc/todo/avoid_thrashing.mdwn b/doc/todo/avoid_thrashing.mdwn new file mode 100644 index 000000000..6c895e7c9 --- /dev/null +++ b/doc/todo/avoid_thrashing.mdwn @@ -0,0 +1,20 @@ +Problem: Suppose a server has 256 mb ram. Each ikiwiki process needs about +15 mb, before it's loaded the index. (And maybe 25 after, but only one such +process runs at any time). That allows for about 16 ikiwiki processes to +run concurrently on a server, before it starts to swap. Of course, anything +else that runs on the server and eats memory will affect this. + +One could just set `MaxClients 16` in the apache config, but then it's also +limited to 16 clients serving static pages, which is silly. Also, 16 is +optimistic -- 8 might be a saner choice. And then, what if something on the +server decides to eat a lot of memory? Ikiwiki can again overflow memory +and thrash. + +It occurred to me that the ikiwiki cgi wrapper could instead do locking of +its own (say of `.ikiwiki/cgilock`). The wrapper only needs a few kb to +run, and it starts *fast*. So hundreds could be running waiting for a lock +with no ill effects. Crank `MaxClients` up to 256? No problem.. + +And there's no real reason to allow more than one ikiwiki cgi to run at a +time. Since almost all uses of the CGI lock the index, only one can really +be doing anything at a time. --[[Joey]] |