Online events: Check-in performance enhancement

[cbellone]

This code increases throughput and adds an hook for customizing the target URL

Here are the results of a load tests performed with siege with the following parameters:

siege -c 250 -b -f <file-with-urls> --no-follow

• 250 concurrent users
• no delay between calls

on a free-of-charge event, with 5000 attendees.

The server has 1 vCPU, 1GB of Ram, running Nginx, Alf.io and PostgreSQL

before:

Transactions:		        3789 hits
Availability:		       96.91 %
Elapsed time:		       98.88 secs
Data transferred:	        0.03 MB
Response time:		        5.58 secs
Transaction rate:	       38.32 trans/sec
Throughput:		        0.00 MB/sec
Concurrency:		      213.73
Successful transactions:        3789
Failed transactions:	         121
Longest transaction:	       39.67
Shortest transaction:	        0.94

after:

Transactions:		        7506 hits
Availability:		      100.00 %
Elapsed time:		       70.86 secs
Data transferred:	        0.00 MB
Response time:		        2.33 secs
Transaction rate:	      105.93 trans/sec
Throughput:		        0.00 MB/sec
Concurrency:		      246.64
Successful transactions:        7506
Failed transactions:	           0
Longest transaction:	       25.98
Shortest transaction:	        0.27