[
https://issues.apache.org/jira/browse/HADOOP-9902?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Allen Wittenauer updated HADOOP-9902:
-------------------------------------
Release Note:
The Hadoop shell scripts have been rewritten to fix many long standing bugs and
include some new features. While an eye has been kept towards compatibility,
some changes may break existing installations.
INCOMPATIBLE CHANGES:
* The pid and out files for secure daemons have been renamed to include the
appropriate ${HADOOP_IDENT_STR}. This should allow, with proper configurations
in place, for multiple versions of the same secure daemon to run on a host.
* All Hadoop shell script subsystems now execute hadoop-env.sh, which allows
for all of the environment variables to be in one location. This was not the
case previously.
* The default content of *-env.sh has been significantly alterated, with the
majority of defaults moved into more protected areas inside the code.
Additionally, these files do not auto-append anymore; setting a variable on the
command line prior to calling a shell command must contain the entire content,
not just any extra settings. This brings Hadoop more in-line with the vast
majority of other software packages.
* All YARN_* and MAPRED_* environment variables act as overrides to their
equivalent HADOOP_* environment variables when 'yarn', 'mapred' and related
commands are executed. Previously, these were separated out which meant a
significant amount of duplication of common settings. * hdfs-config.sh and
hdfs-config.cmd were inadvertently duplicated into libexec and sbin. The sbin
versions have been removed.
* The log4j settings forcibly set by some *-daemon.sh commands have been
removed. These settings are now configurable in the *-env.sh files, in
particular via *_OPT.
* Some formerly documented entries in yarn-env.sh have been undocumented as a
simple form of deprecration in order to greatly simplify configuration and
reduce unnecessary duplication. They will still work, but those variables will
likely be removed in a future release.
* Support for various undocumentented YARN log4j.properties files has been
removed.
* Support for ${HADOOP_MASTER} and the related rsync code have been removed.
* The undocumented yarn.id.str has been removed.
* We now require bash v3 (released July 27, 2004) or better in order to take
advantage of better regex handling and ${BASH_SOURCE}. POSIX sh will not work.
* Support for --script has been removed. We now use ${HADOOP_*_PATH} or
${HADOOP_PREFIX} to find the necessary binaries. (See other note regarding
${HADOOP_PREFIX} auto discovery.)
* Non-existent classpaths, ld.so library paths, JNI library paths, etc, will be
ignored and stripped from their respective environment settings.
BUG FIXES:
* ${HADOOP_CONF_DIR} is now properly honored everywhere.
* ${HADOOP_CONF_DIR}/hadoop-layout.sh is now documented with a provided
hadoop-layout.sh.example file.
* Shell commands should now work properly when called as a relative path,
without ${HADOOP_PREFIX} being defined, and as the target of bash -x for
debugging. If ${HADOOP_PREFIX} is not set, it will be automatically determined
based upon the current location of the shell library. Note that other parts of
the ecosystem may require this environment variable to be configured.
* Operations which trigger ssh will now limit the number of connections to run
in parallel to ${HADOOP_SSH_PARALLEL} to prevent memory and network exhaustion.
By default, this is set to 10.
* ${HADOOP_CLIENT_OPTS} support has been added to a few more commands.
* Some subcommands were not listed in the usage.
* Various options on hadoop command lines were supported inconsistently. These
have been unified into hadoop-config.sh. --config still needs to come first,
however.
* ulimit logging for secure daemons no longer assumes /bin/bash but does assume
bash on the command line path.
* Removed references to some Yahoo! specific paths.
* Removed unused slaves.sh from YARN build tree.
* Many exit states have been changed to reflect reality.
* Shell level errors now go to STDERR. Before, many of them went incorrectly
to STDOUT.
*
IMPROVEMENTS:
* The style and layout of the scripts is now the same. This includes a vast
increase in code comments.
* Significant amounts of redundant code have been moved into a new file called
hadoop-functions.sh.
* The various *-env.sh have been massively changed to include documentation and
examples on what can be set, ramifications of setting, etc. for all variables
that are expected to be set by a user.
* There is now some trivial deduplication and sanitization of the classpath and
JVM options. This allows, amongst other things, for custom settings in *_OPTS
for Hadoop daemons to override defaults and other generic settings (i.e.,
${HADOOP_OPTS}). This is particularly relevant for Xmx settings, as one can
now set them in _OPTS and ignore the heap specific options for daemons which
force the size in megabytes.
* Operations which trigger ssh connections can now use pdsh if installed.
${HADOOP_SSH_OPTS} still gets applied.
* Subcommands have been alphabetized in both usage and in the code.
* All/most of the functionality provided by the sbin/* commands has been moved
to either their bin/ equivalents or made into functions. The rewritten
versions of these commands are now wrappers to maintain backward compatibility.
* Daemonization has been moved from *-daemon.sh to the bin commands via the
--daemon option. Simply use --daemon start to start a daemon, --daemon stop to
stop a daemon, and --daemon status to set $? to the daemon's status.
* It is now possible to override some of the shell code capabilities to provide
site specific functionality without replacing the shipped versions.
* A new option called --buildpaths will attempt to add developer build
directories to the classpath to allow for in source tree testing.
* If a usage function is defined, the following will trigger a help message if
it is given in the option path to the shell script: --? -? ? --help -help -h
help
* Several generic environment variables have been added to provide a common
configuration for pids, logs, and their security equivalents. The older
versions still act as overrides to these generic versions.
* Groundwork has been laid to allow for custom secure daemon setup using
something other than jsvc.
* Added distch and jnipath subcommands to hadoop command.
* By default, ${HADOOP_CONF_DIR} is now at the end of the CLASSPATH.
was:
The Hadoop shell scripts have been rewritten to fix many long standing bugs and
include some new features. While an eye has been kept towards compatibility,
some changes may break existing installations.
INCOMPATIBLE CHANGES:
* The pid, out, etc files for secure daemons have been renamed to include the
appropriate ${HADOOP_IDENT_STR}. This should allow, with proper configurations
in place, for multiple versions of the same secure daemon to run on a host.
* All Hadoop shell script subsystems execute hadoop-env.sh, which allows for
all of the environment variables to be in one location. This was not the case
previously.
* The default content of *-env.sh has been significantly alterated, with the
majority of defaults moved into more protected areas.
* All YARN_* and MAPRED_* environment variables act as overrides to their
equivalent HADOOP_* environment variables when 'yarn', 'mapred' and related
commands are executed. Previously, these were separated out which meant a
significant amount of duplication of common settings.
* hdfs-config.sh and hdfs-config.cmd were inadvertently duplicated into libexec
and sbin. The sbin versions have been removed.
* The log4j settings forcibly set by some *-daemon.sh commands have been
removed. These settings are now configurable in the *-env.sh files, in
particular via *_OPT.
* Support for various undocumentented YARN log4j.properties files has been
removed.
* Support for $HADOOP_MASTER and the related rsync code have been removed.
* yarn.id.str has been removed.
* We now require bash v3 (released July 27, 2004) or better in order to take
advantage of better regex handling and ${BASH_SOURCE}. POSIX sh will not work.
* Support for --script has been removed. We now use ${HADOOP_*_PATH} or
${HADOOP_PREFIX} to find the necessary binaries. (See other note regarding
${HADOOP_PREFIX} auto discovery.)
* Non-existent classpaths, ld.so library paths, JNI library paths, etc, will be
ignored and stripped from their respective environment settings.
BUG FIXES:
* ${HADOOP_CONF_DIR} is now properly honored everywhere.
* Documented hadoop-layout.sh with a provided hadoop-layout.sh.example file.
* Shell commands should now work properly when called as a relative path and
without HADOOP_PREFIX being defined. If ${HADOOP_PREFIX} is not set, it will be
automatically determined based upon the current location of the shell library.
Note that other parts of the ecosystem may require this environment variable to
be configured.
* Operations which trigger ssh will now limit the number of connections to run
in parallel to ${HADOOP_SSH_PARALLEL} to prevent memory and network exhaustion.
By default, this is set to 10.
* ${HADOOP_CLIENT_OPTS} support has been added to a few more commands.
* Various options on hadoop command lines were supported inconsistently. These
have been unified into hadoop-config.sh. --config still needs to come first,
however.
* ulimit logging for secure daemons no longer assumes /bin/bash but does assume
bash on the command line path.
* Removed references to some Yahoo! specific paths.
* Removed unused slaves.sh from YARN build tree.
IMPROVEMENTS:
* Significant amounts of redundant code have been moved into a new file called
hadoop-functions.sh.
* Improved information in the default *-env.sh on what can be set,
ramifications of setting, etc.
* There is an attempt to do some trivial deduplication and sanitization of the
classpath and JVM options. This allows, amongst other things, for custom
settings in *_OPTS for Hadoop daemons to override defaults and other generic
settings (i.e., $HADOOP_OPTS). This is particularly relevant for Xmx settings,
as one can now set them in _OPTS and ignore the heap specific options for
daemons which force the size in megabytes.
* Operations which trigger ssh connections can now use pdsh if installed.
$HADOOP_SSH_OPTS still gets applied.
* Subcommands have been alphabetized in both usage and in the code.
* All/most of the functionality provided by the sbin/* commands has been moved
to either their bin/ equivalents or made into functions. The rewritten
versions of these commands are now wrappers to maintain backward compatibility.
Of particular note is the new --daemon option present in some bin/ commands
which allow certain subcommands to be daemonized.
* It is now possible to override some of the shell code capabilities to provide
site specific functionality.
* A new option called --buildpaths will attempt to add developer build
directories to the classpath to allow for in source tree testing.
* If a usage function is defined, the following will trigger a help message if
it is given in the option path to the shell script: --? -? ? --help -help -h
help
* Several generic environment variables have been added to provide a common
configuration for pids, logs, and their security equivalents. The older
versions still act as overrides to these generic versions.
* Groundwork has been laid to allow for custom secure daemon setup using
something other than jsvc.
* Added distch and jnipath subcommands to hadoop command.
> Shell script rewrite
> --------------------
>
> Key: HADOOP-9902
> URL: https://issues.apache.org/jira/browse/HADOOP-9902
> Project: Hadoop Common
> Issue Type: Improvement
> Components: scripts
> Affects Versions: 3.0.0
> Reporter: Allen Wittenauer
> Assignee: Allen Wittenauer
> Labels: releasenotes
> Attachments: HADOOP-9902-2.patch, HADOOP-9902-3.patch,
> HADOOP-9902-4.patch, HADOOP-9902-5.patch, HADOOP-9902-6.patch,
> HADOOP-9902-7.patch, HADOOP-9902-8.patch, HADOOP-9902.patch, HADOOP-9902.txt,
> hadoop-9902-1.patch, more-info.txt
>
>
> Umbrella JIRA for shell script rewrite. See more-info.txt for more details.
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