How does php detect whether the socket link is broken?

for example, PHP how to detect whether the socket link is broken?

Php socket
Feb.28,2021

the client sends heartbeat packets to the server regularly. If the server does not receive the heartbeat packet for a long time, the client is determined to be offline

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MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-432751c-2ba1.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-432751c-2ba1.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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