in reply to Most memory efficient way to parallel http request

both threads ... with lwp useragent. But I have been facing 'out of memory' issues lately

That almost certainly means you've failed to control the level of concurrency, and/or not discovered/used the threads stacksize => nnnn runtime option. Post your threaded code and we can probably fix that for you.

However, the most memory efficient and fastest mechanism for performing parallel downloads that I've used is LWP::Parallel.

It's not the simplest -- that'd be a thread-pool -- but, used with care and understanding it can easily saturate most broadband connections whilst requiring almost no CPU and very small amounts of memory, and is far simpler than all of the other state-driven modules.

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