The dispatcher calls an operating system function to determine the name of the assigned server for an IP address. While this function is running, the dispatcher, and, therefore, the entire instance, is blocked.
The dispatcher uses Reverse Name Lookup to try to determine the name of the affected server or the GUI terminal when it issues error messages. This is available as an operating system function. During the runtime of this operating system function, the dispatcher is blocked. If it takes several seconds or minutes for the operating system to determine the name or the fact that a name cannot be determined, a standstill of the affected instance may occur.
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The error may always occur when the resolution of IP address names takes too long. When you use the program niping, you can test such name resolutions (niping -v -H <ip address>). The call must return a response immediately.
Set the profile parameter rdisp/reverse_name_lookup to the value 0.
The kernel is changed in such a way that the Reverse Name Lookup is deactivated automatically when an individual call takes longer than 2 seconds or the last ten calls together took longer than 4 seconds.
In the relevant system, you must apply a kernel with a patch level that is at least as high as that specified on the "SP Patch Level" tab page.
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