PiHole DNS Service not running

Expected Behaviour:

PiHole should work with no error, Admin page should be responsive

Actual Behaviour:

Adv still present while navigating, Admin page is really slow to respond to call.
Top left corner of dashboard keep showing “DNS Service not running”, if I press Enable it goes in “Active”, but after a simple refresh it shows again the error.

Debug Token:

https://tricorder.pi-hole.net/kdk1zfiue1

Disable Conditional Forwarding and try things again. PHP is timing out from a long wait time and usually that’s from a huge number of queries to process.

@DL6ER When you have a second:

-----head of pihole-FTL.log------
   [2020-02-24 00:04:26.815 1054] Resizing "/FTL-queries" from 688128 to 917504
   [2020-02-24 00:43:12.734 1054] IPv4 telnet error: Interrupted system call (4)
   [2020-02-24 01:05:42.780 1054] IPv4 telnet error: Interrupted system call (4)
   [2020-02-24 02:05:42.933 15565] Resizing "/FTL-queries" from 917504 to 1146880
   [2020-02-24 02:05:42.999 15566] Remapping "/FTL-queries" from 917504 to 1146880
   [2020-02-24 02:05:43.002 15567] Remapping "/FTL-queries" from 917504 to 1146880
   [2020-02-24 02:05:43.007 15568] Remapping "/FTL-queries" from 917504 to 1146880
   [2020-02-24 02:05:43.009 15569] Remapping "/FTL-queries" from 917504 to 1146880
   [2020-02-24 02:05:43.021 15570] Remapping "/FTL-queries" from 917504 to 1146880
   [2020-02-24 02:05:43.024 15571] Remapping "/FTL-queries" from 917504 to 1146880
   [2020-02-24 02:05:43.028 15572] Remapping "/FTL-queries" from 917504 to 1146880
   [2020-02-24 02:05:43.031 15573] Remapping "/FTL-queries" from 917504 to 1146880
   [2020-02-24 02:05:43.272 1054] Remapping "/FTL-queries" from 917504 to 1146880

Tried right now, it started, I’ll monitor it for a while and see if it holds up. Usually it takes a short time to fall into error again.

This is okay. There are 9 forks with PID 15565 - 15573 and one main process with PID 1054. When one of them needs to resize a shared memory area due to a lot of queries in memory, the others need to remap their memory as the kernel might have moved the memory address in virtual space.

FTL forks for TCP connections to have one dedicated worker for each of these connections. The main process (PID 1054) is the “normal” asynchronous worker for handling UDP requests.

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The service is still up and running, and it seems to me that it’s working fine.
I guess I’ll stick with IP and not Machine Name.

Do you need any info to investigate why Conditional Forwarding was causing that much trouble, or do you prefer to close this issue?

Matteo

Without knowing the details, I assume a DNS loop was created in which your Pi-hole asked your router which in turn asked the Pi-hole which then asks the router which asks the Pi-hole [the story goes on]

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