On some Linux distributions tmpfiles.d cleans files and
directories under /tmp if they haven't been accessed for
10 days.
This can cause problems for ML as ML is currently the only
component that uses the temp directory more than a few
seconds after startup. If you didn't open an ML job for
10 days and then tried to open one then the temp directory
would have been deleted.
This commit prevents the problem occurring in the case of
Elasticsearch being managed by systemd, as systemd private
temp directories are not subject to periodic cleanup (by
default).
Additionally there are now some docs to warn people about
the risk and suggest a manual mitigation for .tar.gz users.
This commit reorganizes some of the content in the configuring
Elasticsearch section of the docs. The changes are:
- move JVM options out of system configuration into configuring
Elasticsearch
- move JVM options to its own page of the docs
- move configuring the heap to important Elasticsearch settings
- move configuring the heap to its own page of the docs
- move all important settings to individual pages in the docs
- remove bootstrap.memory_lock from important settings, this is covered
in the swap section of system configuration
Relates #27755
For too long we have been groping around in the dark when faced with GC
issues because we rarely have GC logs at our disposal. This commit
enables GC logging by default out of the box.
Relates #27610
When these docs were moved they should have been moved to the system
configuration docs. This commit does that, and also fixes a missing
heading that broke the docs build.
The JVM defaults to dumping the heap to the working directory of
Elasticsearch. For the RPM and Debian packages, this location is
/usr/share/elasticsearch. This directory is not writable by the
elasticsearch user, so by default heap dumps in this situation are
lost. This commit modifies the packaging for the RPM and Debian packages
to set the heap dump path to /var/lib/elasticsearch as the default
location for dumping the heap. This location is writable by the
elasticsearch user by default. We add documentation of this important
setting if /var/lib/elasticsearch is not suitable for receiving heap
dumps.
Relates #26755
Today when you do not specify a port for an entry in
discovery.zen.ping.unicast.hosts, the default port is the value of the
setting transport.profiles.default.port and falls back to the value of
transport.tcp.port if this is not set. For a node that is explicitly
bound to a different port than the default port, this means that the
default port will be equal to this explicitly bound port. Yet, the docs
say that we fall back to 9300 here. This commit corrects the docs.
Relates #22568
The important settings docs previously referred to a section regarding
the node.max_local_storage_nodes setting. This section was removed, but
the link was not. This commit removes that link.
Previously node.max_local_storage_nodes defaulted to fifty, and this
permitted users to start multiple instances of Elasticsearch sharing the
same data folder. This can be dangerous, and usually it does not make
sense to run more than one instance of Elasticsearch on a single
server. Because of this, we had a note in the important settings docs
advising users to set this setting to one. However, we have since
changed the default value of this setting to one so this advise is no
longer needed.
Relates #21305
With #19140 we started persisting the node ID across node restarts. Now that we have a "stable" anchor, we can use it to generate a stable default node name and make it easier to track nodes over a restarts. Sadly, this means we will not have those random fun Marvel characters but we feel this is the right tradeoff.
On the implementation side, this requires a bit of juggling because we now need to read the node id from disk before we can log as the node node is part of each log message. The PR move the initialization of NodeEnvironment as high up in the starting sequence as possible, with only one logging message before it to indicate we are initializing. Things look now like this:
```
[2016-07-15 19:38:39,742][INFO ][node ] [_unset_] initializing ...
[2016-07-15 19:38:39,826][INFO ][node ] [aAmiW40] node name set to [aAmiW40] by default. set the [node.name] settings to change it
[2016-07-15 19:38:39,829][INFO ][env ] [aAmiW40] using [1] data paths, mounts [[ /(/dev/disk1)]], net usable_space [5.5gb], net total_space [232.6gb], spins? [unknown], types [hfs]
[2016-07-15 19:38:39,830][INFO ][env ] [aAmiW40] heap size [1.9gb], compressed ordinary object pointers [true]
[2016-07-15 19:38:39,837][INFO ][node ] [aAmiW40] version[5.0.0-alpha5-SNAPSHOT], pid[46048], build[473d3c0/2016-07-15T17:38:06.771Z], OS[Mac OS X/10.11.5/x86_64], JVM[Oracle Corporation/Java HotSpot(TM) 64-Bit Server VM/1.8.0_51/25.51-b03]
[2016-07-15 19:38:40,980][INFO ][plugins ] [aAmiW40] modules [percolator, lang-mustache, lang-painless, reindex, aggs-matrix-stats, lang-expression, ingest-common, lang-groovy, transport-netty], plugins []
[2016-07-15 19:38:43,218][INFO ][node ] [aAmiW40] initialized
```
Needless to say, settings `node.name` explicitly still works as before.
The commit also contains some clean ups to the relationship between Environment, Settings and Plugins. The previous code suggested the path related settings could be changed after the initial Environment was changed. This did not have any effect as the security manager already locked things down.
The setting bootstrap.mlockall is useful on both POSIX-like systems
(POSIX mlockall) and Windows (Win32 VirtualLock). But mlockall is really
a POSIX only thing so the name should not be tied POSIX. This commit
renames the setting to "bootstrap.memory_lock".
Relates #18669
David Roberts
Jason Tedor
Clinton Gormley
Pascal Borreli
Boaz Leskes