Split your bigfile size across N machines.
Have a process on each machine that processes a filesize/N chunk of the bigfile. (Say, 32 machines each reading a different 32GB chunk of your 1TB file.)
Each reader accumulates word counts in a hash until the hash size approaches it's memory limit.
(Assume ~1.5GB/10 million words/keys on a 64-bit Perl; somewhat less on a 32-bit.)
When that limit is reached; it posts (probably udp) out the word/count pairs to the appropriate accumulator machines; frees the hash and continues reading the file from where it left off.
- The file is only processed once.
- It can be processed in parallel by as many reader processes/machines as your IO/Disk bandwidth will allow.
- Each reader process only uses whatever amount of memory you decide is the limit.
- You can split the accumulations across as many (or few) boxes as are required.
- As only word/count pairs are exchanged, IO (other than reading the file) will be minimal.
No threading, shared memory or locking required. Simple to set up and efficient to process.
With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
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