PHP scripts executing multiple times from a single HTTP request

Question

So Http uses TCPIP and that has automatic retries. I saw some behavior where a message appears to have hit the server 3 times at the same time. I am wondering if during poor connections, will the TCPIP retry trigger extra PHP calls?

If this is the case, how does one avoid duplicating effort? I have safeguards upon repeating the same transaction, but if they arrive at the exact same instant its much harder to do that.

Please provide your data source linking the extra calls and etc. — user924016
– user924016, Commented Nov 12, 2015 at 21:26
I don't now if this help or if that is your case, but as far as i now , tcp/ip is trasparent to request because is a protocol layer and it's more deeper .. i saw this behaviors specially when you're doing Ajax requests and the events are not well coded... — Joaquin Javi
– Joaquin Javi, Commented Nov 12, 2015 at 21:34

Barmar · Accepted Answer · 2015-11-12 21:36:53Z

2

No, TCP retransmission won't duplicate the requests. TCP retransmission occurs within the context of a single connection, it doesn't create multiple connections. And the retransmitted segments have the same sequence numbers as the original segments; if the server receives both of them (i.e. the lost segment was the acknowledgement), it can tell that the second one is a duplicate and it will ignore it automatically.

answered Nov 12, 2015 at 21:36

Barmar

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