javascript - Will Node.js get blocked when processing large file uploads? -


will node.js blocked when processing large file uploads?

since node.js has 1 thread, true when doing large file uploads other requests blocked?

if so, how should handle file uploads in nodejs?

all i/o operations handled node.js using multiple threads internally; it's programming interface i/o functionality that's single threaded, event-based, , asynchronous.

so big upload of example performed separate thread that's managed node.js, , when thread completes work, callback put onto event loop queue.

when cpu intensive task blocks. let's have task compute() needs run continuously, , cpu intensive calculations.

answer main question "how should handle file uploads in nodejs?"
check in code (or library) save file on server, dependent on writefile() or writefilesync()?
if using writefile() asynchronous; if writefilesync() synchronous version.

updates: in response comment:

"the answer "no, won't block" correct explanation wrong. js in 1 thread , i/o in 1 (same) thread. event loop / asynchronous processing / callbacks make possible. no multiple threads required. " - andrey-sidorov

there no async api file operations node.js uses thread pool that. can see in code of libuv. can @ source fs.readfile in lib/fs.js, you’ll see binding.read. whenever see binding in node’s core modules you’re looking @ portal land of c++. binding made available using node_set_method(target, "read", read). if know c, might think macro – originally, it’s function.

going async_call in read, 1 of arguments read: the syscall read. wait, doesn't function block?

yes, that’s not end of story. introduction libuv denotes following:

"the libuv filesystem operations different socket operations. socket operations use non-blocking operations provided operating system. filesystem operations use blocking functions internally, but invoke these functions in thread pool , notify watchers registered event loop when application interaction required."

summary: node api method writefile() asynchronous, doesn’t mean it’s non-blocking underneath. libuv book points out, socket (network) code non-blocking, filesystems more complicated. things event-based (kqueue), others use thread pool (as in case).

consider going through c code on node.js developed, more information:


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