Apache 2.4, CPU rodando a 100% por motivo desconhecido

Question

Estou tentando descobrir por que meu servidor tem um consumo de CPU tão alto vindo do Apache 2.4.Estou no Ubuntu 16 .

Aqui está o que vejo atualmente em "top":

root@mail:~# top
top - 12:54:47 up 42 min,  2 users,  load average: 1.96, 1.94, 1.97
Tasks: 178 total,   3 running, 175 sleeping,   0 stopped,   0 zombie
%Cpu(s): 43.5 us, 56.5 sy,  0.0 ni,  0.0 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
KiB Mem :  2044912 total,   214760 free,  1316416 used,   513736 buff/cache
KiB Swap:   262140 total,   255940 free,     6200 used.   638968 avail Mem

  PID USER      PR  NI    VIRT    RES    SHR S %CPU %MEM     TIME+ COMMAND
 6541 www-data  20   0  721368 112640   8528 R 49.8  5.5   1:16.68 /usr/sbin/apach
 6542 www-data  20   0  522556 103532   3504 R 49.8  5.1   1:16.60 /usr/sbin/apach
 3532 mysql     20   0 1112464 151152  17516 S  0.3  7.4   0:01.45 mysqld
 3674 jetty     20   0 2329684 213996  18208 S  0.3 10.5   0:15.11 java
 4526 root      20   0   95404   6776   5836 S  0.3  0.3   0:00.16 sshd
 5866 root      20   0   41816   3888   3172 R  0.3  0.2   0:01.02 top

Depois de pesquisar on-line, encontrei o recurso strace -p PID . Eu corro isso em um dos processos ofensivos, e eu centenas de milhares disso:

read(2, 0x7ffcae1de7d3, 1)              = -1 EBADF (Bad file descriptor)
read(2, 0x7ffcae1de7d3, 1)              = -1 EBADF (Bad file descriptor)
read(2, 0x7ffcae1de7d3, 1)              = -1 EBADF (Bad file descriptor)
read(2, 0x7ffcae1de7d3, 1)              = -1 EBADF (Bad file descriptor)
read(2, 0x7ffcae1de7d3, 1)              = -1 EBADF (Bad file descriptor)
read(2, 0x7ffcae1de7d3, 1)              = -1 EBADF (Bad file descriptor)
read(2, 0x7ffcae1de7d3, 1)              = -1 EBADF (Bad file descriptor)
read(2, 0x7ffcae1de7d3, 1)              = -1 EBADF (Bad file descriptor)
read(2, 0x7ffcae1de7d3, 1)              = -1 EBADF (Bad file descriptor)
read(2, 0x7ffcae1de7d3, 1)              = -1 EBADF (Bad file descriptor)

Tentei voltar ao início do processo (para ver o que está acontecendo), mas não consigo responder rápido o suficiente!

Tem 2 GB de RAM e 1 CPU, com uma unidade SSD.

Como sugerido, testei os mesmos processos com o gdb e obtive este erro:

../sysdeps/unix/syscall-template.S: No such file or directory.

Me deparei com este post:

link

Eles sugerem fazer:

sudo apt-get install eglibc-source

Não consegui encontrar esse pacote, mas encontrei glibc-source , então instalei esse pacote. Infelizmente, ainda recebo o mesmo erro (mesmo depois de reiniciar);

84      ../sysdeps/unix/syscall-template.S: No such file or directory.

Fazendo um pouco mais de escavação, posso ver:

root@mail:~# gdb --pid=7708
GNU gdb (Ubuntu 7.11.1-0ubuntu1~16.04) 7.11.1
Copyright (C) 2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word".
Attaching to process 7708
[New LWP 7712]
[New LWP 7713]
[New LWP 7714]
[New LWP 7715]
[New LWP 7716]
[New LWP 7717]
[New LWP 7718]
[New LWP 7719]
[New LWP 7720]
[New LWP 7721]
[New LWP 7722]
[New LWP 7723]
[New LWP 7724]
[New LWP 7725]
[New LWP 7726]
[New LWP 7727]
[New LWP 7728]
[New LWP 7729]
[New LWP 7730]
[New LWP 7731]
[New LWP 7732]
[New LWP 7733]
[New LWP 7734]
[New LWP 7735]
[New LWP 7736]
[New LWP 7737]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
0x00007fcc946f051d in read () at ../sysdeps/unix/syscall-template.S:84
84      ../sysdeps/unix/syscall-template.S: No such file or directory.
(gdb) n
86      in ../sysdeps/unix/syscall-template.S
(gdb) n
0x000055b4134ed9b7 in ap_mpm_podx_check ()
(gdb) n
Single stepping until exit from function ap_mpm_podx_check,
which has no line number information.
0x00007fcc9163935b in ?? () from /usr/lib/apache2/modules/mod_mpm_event.so
(gdb) n
Cannot find bounds of current function
(gdb)

Eu também tenho glibc-source instalado, por isso estou confuso sobre o porquê de ele ter esse erro:

root@mail:~# apt-get install glibc-source
Reading package lists... Done
Building dependency tree
Reading state information... Done
glibc-source is already the newest version (2.23-0ubuntu7).
0 upgraded, 0 newly installed, 0 to remove and 7 not upgraded.

Se eu fizer um locate syscall-template.S , não obtenho resultados (mesmo depois de executar updatedb ), então estou supondo que está faltando, mas não tenho certeza do porquê)

Ainda não sei o que isso significa: /