|laziness, impatience, and hubris|
Re^3: problem of my multithreading perl scriptby roboticus (Chancellor)
|on Jan 11, 2013 at 13:48 UTC||Need Help??|
No, there are multiple ways that a threaded program can be slower than a single threaded program. In this case, I don't know exactly which one(s) you're hitting, but there are two candidates I can think of:
Having said that, you can probably speed things up without going to a single-threaded program.
If your program is experiencing disk thrashing, you might be able to avoid it by placing your files on different drives. That way you won't have as many disk seeks.
If your program is spending too much time managing data structure locks, you might be able to rearrange your code a bit to reduce the number of locks. For example, you might have each thread read and process a file in a local (nonshared) data structure, and then once it's finished a file, then merge the data into the shared structure.
There are other possible problems and solutions to your problem, these are just the ones that came to mind. (I've run into both of them frequently enough...unfortunately.)
When your only tool is a hammer, all problems look like your thumb.