A test harness to play around with PHP's Memcached client and persistent connections in Apache/mod_php.
script/setup starts up an Apache server with 5 workers and a fake Memcached
server that only responds to the command get foo. Any other requests hangs
indefinitely so you can explore PHP's Memcached client timeouts.
The Memcached server logs commands as they're received to paint a picture of what the PHP client is doing. For example, the following request:
$ curl http://localhost:8080/00-no-pool.php
string(3) "bar"
yields the logs:
fakememcached_1 | 2019/11/18 22:00:22 172.21.0.3:53570: Got message "get foo\r\n"
fakememcached_1 | 2019/11/18 22:00:22 172.21.0.3:53570: Got message "quit\r\n"
fakememcached_1 | 2019/11/18 22:00:22 172.21.0.3:53570: Closing connection
where 172.21.0.3:53570 is the source IP and port of the connection.
Notice instead, if you request 01-pool.php, you will see that the connections
are left open and that the requests round-robin through the 5 Apache workers.
02-bad-no-pool.php consistently takes 5 seconds:
$ time curl http://localhost:8080/02-bad-no-pool.php
string(51) "SERVER HAS FAILED AND IS DISABLED UNTIL TIMED RETRY"
curl http://localhost:8080/02-bad-no-pool.php 0.00s user 0.00s system 0% cpu 5.021 total
03-bad-pool.php takes 5 seconds for the first 5 requests (one to warm up each
Apache worker) then will return immediately for the next 100 seconds,
OPT_RETRY_TIMEOUT.
$ time curl http://localhost:8080/03-bad-pool.php
string(51) "SERVER HAS FAILED AND IS DISABLED UNTIL TIMED RETRY"
curl http://localhost:8080/03-bad-pool.php 0.00s user 0.00s system 49% cpu 0.016 total