when forking: close FDs in optimized way

[mighq]

• exec plugind & collectdmon patched
• code ported from sudo utility

Problem was occurring when fs.file-max sysctl option was set to really high number (millions). In combination with fork-every-time exec data sources, it was spending too much time in CPU doing millions of unneccessary close() calls.

ChangeLog: exec plugin: optimized way (faster) of closing the file descriptors

[peterbowey]

Patch 3f847de has an error within this section (based @ current collectd master release):

diff --git a/src/Makefile.am b/src/Makefile.am
index a9d8582..029a898 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -22,6 +22,7 @@ bin_PROGRAMS = collectd-nagios collectdctl collectd-tg

 collectd_SOURCES = collectd.c collectd.h \
           common.c common.h \
+          compat/closefrom.c \
           configfile.c configfile.h \
           filter_chain.c filter_chain.h \
           meta_data.c meta_data.h \
@@ -87,7 +88,7 @@ else
 collectd_LDADD += -loconfig
 endif

-collectdmon_SOURCES = collectdmon.c
+collectdmon_SOURCES = collectdmon.c compat/closefrom.c
 collectdmon_CPPFLAGS = $(AM_CPPFLAGS)

 collectd_nagios_SOURCES = collectd-nagios.c

The patch section -22,6 +22,7 (for Makefile.am) needs removing.
The new resulting '/src/Makefile.am' patch would be:

diff --git a/src/Makefile.am b/src/Makefile.am
index a9d8582..029a898 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -87,7 +88,7 @@ 
 sbin_PROGRAMS = collectdmon
 bin_PROGRAMS = collectd-nagios collectdctl collectd-tg

-collectdmon_SOURCES = collectdmon.c
+collectdmon_SOURCES = collectdmon.c compat/closefrom.c
 collectdmon_CPPFLAGS = $(AM_CPPFLAGS)

 collectd_nagios_SOURCES = collectd-nagios.c

Modified (local) Pull #934 Tested OK @ current collectd master.

[mighq]

manually "rebased" the patch on top of 5.9 sources and then merged current master