How can I synchronize access to an appender?
If you’re using the same instance of an appender in multiple processes, and each process is passing on messages to the appender in parallel, you might end up with overlapping log entries. Typical scenarios include a file appender that you create in the main program, and which will then be shared between the parent and a forked child process. Or two separate processes, each initializing a Log4perl file appender on the same logfile. Log::Log4perl won’t synchronize access to the shared logfile by default. Depending on your operating system’s flush mechanism, buffer size and the size of your messages, there’s a small chance of an overlap. The easiest way to prevent overlapping messages in logfiles written to by multiple processes is setting the file appender’s syswrite flag along with a file write mode of “append”. This makes sure that Log::Log4perl::Appender::File uses syswrite() (which is guaranteed to run uninterrupted) instead of print() which might buffer the message or get interrupte
If you’re using the same instance of an appender in multiple processes, and each process is passing on messages to the appender in parallel, you might end up with overlapping log entries. Typical scenarios include a file appender that you create in the main program, and which will then be shared between the parent and a forked child process. Or two separate processes, each initializing a Log4perl file appender on the same logfile. Log::Log4perl won’t synchronize access to the shared logfile by default. Depending on your operating system’s flush mechanism, buffer size and the size of your messages, there’s a small chance of an overlap. The easiest way to prevent overlapping messages in logfiles written to by multiple processes is setting the file appender’s “syswrite” flag along with a file write mode of “append”. This makes sure that “Log::Log4perl::Appender::File” uses “syswrite()” (which is guaranteed to run uninterrupted) instead of “print()” which might buffer the message or get in
