Author: tomwhite
Date: Wed Apr 3 18:01:14 2013
New Revision: 1464130
URL: http://svn.apache.org/r1464130
Log:
YARN-381. Improve fair scheduler docs. Contributed by Sandy Ryza.
Modified:
hadoop/common/trunk/hadoop-yarn-project/CHANGES.txt
hadoop/common/trunk/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/FairScheduler.apt.vm
Modified: hadoop/common/trunk/hadoop-yarn-project/CHANGES.txt
URL:
http://svn.apache.org/viewvc/hadoop/common/trunk/hadoop-yarn-project/CHANGES.txt?rev=1464130&r1=1464129&r2=1464130&view=diff
==============================================================================
--- hadoop/common/trunk/hadoop-yarn-project/CHANGES.txt (original)
+++ hadoop/common/trunk/hadoop-yarn-project/CHANGES.txt Wed Apr 3 18:01:14 2013
@@ -115,6 +115,8 @@ Release 2.0.5-beta - UNRELEASED
YARN-447. Move ApplicationComparator in CapacityScheduler to use comparator
in ApplicationId. (Nemon Lou via vinodkv)
+ YARN-381. Improve fair scheduler docs. (Sandy Ryza via tomwhite)
+
OPTIMIZATIONS
BUG FIXES
Modified:
hadoop/common/trunk/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/FairScheduler.apt.vm
URL:
http://svn.apache.org/viewvc/hadoop/common/trunk/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/FairScheduler.apt.vm?rev=1464130&r1=1464129&r2=1464130&view=diff
==============================================================================
---
hadoop/common/trunk/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/FairScheduler.apt.vm
(original)
+++
hadoop/common/trunk/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/FairScheduler.apt.vm
Wed Apr 3 18:01:14 2013
@@ -85,8 +85,9 @@ Hadoop MapReduce Next Generation - Fair
cause too much intermediate data to be created or too much context-switching.
Limiting the apps does not cause any subsequently submitted apps to fail,
only to wait in the scheduler's queue until some of the user's earlier apps
- finish. apps to run from each user/queue are chosen in order of priority and
- then submit time, as in the default FIFO scheduler in Hadoop.
+ finish. Apps to run from each user/queue are chosen in the same fair sharing
+ manner, but can alternatively be configured to be chosen in order of submit
+ time, as in the default FIFO scheduler in Hadoop.
Certain add-ons are not yet supported which existed in the original (MR1)
Fair Scheduler. Among them, is the use of a custom policies governing
@@ -142,7 +143,9 @@ Hadoop MapReduce Next Generation - Fair
* <<<yarn.scheduler.fair.sizebasedweight>>>
* Whether to assign shares to individual apps based on their size, rather
than
- providing an equal share to all apps regardless of size. Defaults to
false.
+ providing an equal share to all apps regardless of size. When set to
true,
+ apps are weighted by the natural logarithm of one plus the app's total
+ requested memory, divided by the natural logarithm of 2. Defaults to
false.
* <<<yarn.scheduler.fair.assignmultiple>>>
@@ -180,16 +183,29 @@ Allocation file format
* <<Queue elements>>, which represent queues. Each may contain the following
properties:
- * minResources: minimum amount of aggregate memory
+ * minResources: minimum MB of aggregate memory the queue expects. If a queue
+ demands resources, and its current allocation is below its configured
minimum,
+ it will be assigned available resources before any queue that is not in
this
+ situation. If multiple queues are in this situation, resources go to the
+ queue with the smallest ratio between allocation and minimum. Note that
it is
+ possible that a queue that is below its minimum may not immediately get
up to
+ its minimum when it submits an application, because already-running jobs
may
+ be using those resources.
- * maxResources: maximum amount of aggregate memory
+ * maxResources: maximum MB of aggregate memory a queue is allowed. A queue
+ will never be assigned a container that would put it over this limit.
* maxRunningApps: limit the number of apps from the queue to run at once
- * weight: to share the cluster non-proportionally with other queues
+ * weight: to share the cluster non-proportionally with other queues. Weights
+ default to 1, and a queue with weight 2 should receive approximately twice
+ as many resources as a queue with the default weight.
* schedulingMode: either "fifo" or "fair" depending on the in-queue
scheduling
- policy desired
+ policy desired. Defaults to "fair". If "fifo", apps with earlier submit
+ times are given preference for containers, but apps submitted later may
+ run concurrently if there is leftover space on the cluster after
satisfying
+ the earlier app's requests.
* aclSubmitApps: a list of users that can submit apps to the queue. A
(default)
value of "*" means that any users can submit apps. A queue inherits the
ACL of
