Windows 1024 Connections Limit

Maxim Dounin mdounin at
Wed Apr 12 12:57:16 UTC 2017


On Tue, Apr 11, 2017 at 09:37:46PM -0700, Igal @ wrote:

> Is there a technical reason for the 1,024 Connections Limit on Windows?
> Surely the OS can handle many more connections than that.

On Windows, nginx uses select() system call to handle connection 
events.  This syscall implies fixed-size bitmasks to pass file 
descriptors from userland to kernel and back.  Size of these 
bitmasks can be only specified during compilation, and 1024 is the 
value nginx uses for official binaries to balance between maximum 
number of connections and unneeded overhead implied by large 

> This is not much of an issue with regular requests, but when you use 
> WebSockets you can run out of connections very fast.

It is possible to recompile nginx with different value if you need 
to, see

On ther other hand, if you are using nginx in production I would 
recommend to consider using Unix variants instead.

Maxim Dounin

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