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English
PHP's closelog() is idempotent, meaning it won't cause errors if called multiple times. However, this could mask issues in the program where resources are being cleaned up repeatedly. For example, if a function is called multiple times but closelog() is executed each time, it may indicate unclear resource management logic.
Troubleshooting Method:
Encapsulate log-related calls to avoid calling closelog() in multiple places.
Use a log wrapper class or pattern (e.g., singleton) to centrally control the log connection lifecycle.
The logging system may have buffering after syslog(). Calling closelog() immediately after can prevent the log from being written in time, especially in high-concurrency or special environments.
Troubleshooting Method:
Introduce a delay after calling syslog() (only for debugging purposes, not recommended for production);
Try to call closelog() at the end of the script or during the destruction phase, rather than immediately after each log entry.
openlog("example", LOG_PID | LOG_PERROR, LOG_LOCAL0);
syslog(LOG_INFO, "Test log entry");
// Do not call closelog() immediately, instead call it at the end of the script
Sometimes, even when closelog() is called correctly, the log may not be written. The possible reason could be that openlog() is using an invalid log type (facility) or the system hasn't enabled logging permissions for that type.
Troubleshooting Method:
Check if the facility used in openlog() is supported by the system;
Check the system's syslog configuration files (e.g., /etc/rsyslog.conf or /etc/syslog.conf) to see if the corresponding facility is enabled;
Check the log file permissions or use the logger command to manually test.
