Failed to map segment from shared object: Cannot allocate memory

apache-2.2

early this morning there was a log rotation, the last line in the apache error log was:

 [error] (9)Bad file descriptor: apr_socket_accept: (client socket)    apache2: Syntax error on line 250 of /etc/apache2/apache2.conf: Syntax error on line 1 of /etc/apache2/mods-enabled/alias.load: Cannot load /usr/lib/apache2/modules/mod_alias.so into server: /usr/lib/apache2/modules/mod_alias.so: failed to map segment from shared object: Cannot allocate memory

Apache failed to auto reload after this. When I got around to looking at this an hour or so later, i simply did an apache restart and everything was fine. It did leave a warning in the new log file:

[warn] pid file /var/run/apache2.pid overwritten -- Unclean shutdown of previous Apache run?

What does this mean, and how can I correct what ever went wrong?

(Apache/2.2.22 (Debian))

edit
or if this is not something that can be fixed, is there a way of getting apache to auto reload x qty of times before giving up (like pm2 with node)?

Best Answer

An inability to allocate shared memory is a special kind of beast. It doesn't mean that the system as a whole is out of memory, but instead that you've hit one of the limits that govern shared memory allocation.

The two relevant sysctls are kernel.shmmax (which is the limit, in bytes, on how large a single shared memory segment can be) and kernel.shmall (which is the total amount of shared memory, in bytes, that can be allocated to the system). Use grep Shmem /proc/meminfo; cat /proc/sys/kernel/shmall to visualize these amounts.

You can tell whether shmall has been hit by comparing the Shmem line of /proc/meminfo against /proc/sys/kernel/shmall. If they're about equal, then you've hit the system-wide shared memory limit, and will need to increase kernel.shmall (or stop something that's got shared memory in use). Otherwise, you'll probably need to increase kernel.shmmax to something larger than whatever the process that's failing wants to use.

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Compiling Apache mod_ssl for different target hardware (hardware capability unsupported SSE2 error)

Here are the steps that I have done to successfully build and install the Apache httpd-2.4.10 and OpenSSL openssl-1.0.1j on Solaris 10.

Download following software
openssl-1.0.1j.tar.gz
httpd-2.4.10.tar.gz
apr-1.5.1.tar.gz
apr-util-1.5.4.tar.gz
pcre-8.36.tar.gz
Verify Make and CC
By default gcc is at /usr/sfw/bin/gcc and make is at /usr/ccs/bin/make

Include following in the PATH
usr/local/ssl/bin:/usr/sfw/bin:/usr/local/bin:/usr/ccs/bin

Include following in the LD_LIBRARY_PATH
/usr/local/lib:/usr/local/ssl/lib
Build and install openssl-1.0.1j
Unzip and un-tar openssl-1.0.1j.tar.gz to /usr/local/openssl-1.0.1j
Execute following commands in order. The shared parameter is very important so that it can be linked with httpd-2.4.10 build for SSL enabling.
```
$ cd /usr/local/openssl-1.0.1j
$ ./config shared
$ make
$ make test
$ make install
```
By default it installs openssl at /usr/local/ssl
Install pcre-8.36 Unzip and un-tar pcre-8.36.tar.gz to /usr/local/ pcre-8.36

Execute following commands in order
```
$ cd /usr/local/ pcre-8.36
$ ./configure 
$ make
$ make install
```
By default, make install installs the package's commands under /usr/local/bin, include files under /usr/local/include, etc.
Build and install httpd-2.4.10

Unzip and un-tar httpd-2.4.10.tar.gz to /usr/local/httpd-2.4.10

Unzip and un-tar apr-1.5.1.tar.gz to /usr/local/httpd-2.4.10/srclib
Rename /usr/local/apr-1.5.1 to /usr/local/apr

Unzip and un-tar apr-util-1.5.4.tar.gz to /usr/local/httpd-2.4.10/srclib
Rename /usr/local/apr-util to /usr/local/apr-util

Execute following commands in order
```
$ ./configure --prefix=/usr/local/apache2 --with-included-apr --enable-so –enable-ssl=shared --with-ssl=/usr/local/ssl
$ make
$ make install
```
It installs it at /usr/local/apache2

The installation is complete. To enable SSL and Proxy, update /usr/local/apache2/conf/httpd.conf with uncommentting following lines

LoadModule socache_shmcb_module modules/mod_socache_shmcb.so

LoadModule proxy_module modules/mod_proxy.so
LoadModule proxy_connect_module modules/mod_proxy_connect.so
LoadModule proxy_ftp_module modules/mod_proxy_ftp.so
LoadModule proxy_http_module modules/mod_proxy_http.so
LoadModule proxy_fcgi_module modules/mod_proxy_fcgi.so
LoadModule proxy_scgi_module modules/mod_proxy_scgi.so
LoadModule proxy_wstunnel_module modules/mod_proxy_wstunnel.so
LoadModule proxy_ajp_module modules/mod_proxy_ajp.so
LoadModule proxy_balancer_module modules/mod_proxy_balancer.so
LoadModule proxy_express_module modules/mod_proxy_express.so

LoadModule slotmem_shm_module modules/mod_slotmem_shm.so
LoadModule ssl_module modules/mod_ssl.so

Include conf/extra/httpd-ssl.conf

Now you can work on httpd-ssl.conf as you usually do to complete your configuration

Best Answer

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