Application BUG: Has sigchld set to sig_ign but callwait ()

The following error logs are displayed in the system logs of a Linux machine:

Kernel: Application BUG:ProgramName (row number) has sigchld set to sig_ign but callwait ()

Generally, the sigchld signal is the signal sent by the kernel to the parent process when the child process ends. Normally, the parent process calls the wait function to collect the status information of the child process and release the child process resources.

For some concurrent servers, many sub-processes are often fork. To save time, the signal processing method of the sigchld is set to ignore, so that the kernel can forward the zombie sub-process to the INIT process for processing, eliminating the need for a large number of zombie processes to occupy system resources. If wait is still called in this case, this error will occur.