[erlang-questions] Erlang accepting SSL connection is really slow (comparing to C++)

Loïc Hoguin <>
Tue Apr 10 17:56:53 CEST 2012


Hello!

On 04/10/2012 05:27 PM, SEGALIS Morgan wrote:
[...]
> While it will take 10 second to a ssl accepting bit of C++ code to accept
> all of them (which don't even have multiple accept pending), in Erlang this
> is quite different. It will accept at most 20 connections a second
> (according to netstat info, whilst C++ accept more like 1K connection per
> seconds)
>
> While the 10K connections are awaiting for acceptance, I'm manually trying
> to connect as well.
>
>      openssl s_client -ssl3 -ign_eof -connect myserver.com:4242
>
> 3 cases happen when I do :
>
>   - Connection simply timeout
>   - Connection will connect after waiting for it 30 sec. at least
>   - Connection will occur almost directly

The OTP SSL code is just very slow, and AFAIK the reason for this is 
that it's done in full Erlang. Here's a quick and dirty comparison 
between HTTP and HTTPS in Cowboy, where only the transport used differs:

HTTP:

% siege -b -c 100 http://localhost:8080/
** SIEGE 2.70
** Preparing 100 concurrent users for battle.
The server is now under siege...^C
Lifting the server siege...      done.
Transactions:		       49266 hits
Availability:		      100.00 %
Elapsed time:		        5.94 secs
Data transferred:	        0.56 MB
Response time:		        0.01 secs
Transaction rate:	     8293.94 trans/sec
Throughput:		        0.09 MB/sec
Concurrency:		       99.36
Successful transactions:       49266
Failed transactions:	           0
Longest transaction:	        0.06
Shortest transaction:	        0.00

HTTPS:

% siege -b -c 100 https://localhost:8443/
** SIEGE 2.70
** Preparing 100 concurrent users for battle.
The server is now under siege...^C
Lifting the server siege...      done.
Transactions:		         698 hits
Availability:		      100.00 %
Elapsed time:		        4.50 secs
Data transferred:	        0.01 MB
Response time:		        0.59 secs
Transaction rate:	      155.11 trans/sec
Throughput:		        0.00 MB/sec
Concurrency:		       92.15
Successful transactions:         698
Failed transactions:	           0
Longest transaction:	        1.14
Shortest transaction:	        0.07

This is on a Zenbook UX31E which is a damn good machine but it still 
shows a huge difference between both of them. And the more you try to 
accept at the same time, the longest time it can take to accept.

-- 
Loïc Hoguin
Erlang Cowboy
Nine Nines



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