1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
|
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.drill.yarn.appMaster;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* Abstract base class for schedulers that work with persistent
* (long-running) tasks. Such tasks are intended to run until
* explicitly shut down (unlike batch tasks that run until
* some expected completion.)
* <p>
* Provides a target quantity of tasks
* (see {@link #getTarget()}, along with operations to increase,
* decrease or set the target number.
* <p>
* The scheduler acts as a controller: starting new tasks as needed to
* match the desired target, or stopping tasks as needed when the
* target level is reduced.
*/
public abstract class PersistentTaskScheduler extends AbstractScheduler {
private static final Log LOG = LogFactory.getLog(PersistentTaskScheduler.class);
protected int quantity;
public PersistentTaskScheduler(String type, String name, int quantity) {
super(type, name);
this.quantity = quantity;
}
/**
* Set the number of running tasks to the quantity given.
*
* @param level
* the target number of tasks
*/
@Override
public int resize(int level) {
quantity = level;
if (quantity < 0) {
quantity = 0;
}
return quantity;
}
@Override
public int getTarget() { return quantity; }
/**
* Indicate that a task is completed. Normally occurs only
* when shutting down excess tasks.
*
* @param task
*/
@Override
public void completed(Task task) { }
/**
* Progress for persistent tasks defaults to the ratio of
* running tasks to target level. Thus, a persistent cluster
* will normally report 100% progress.
*
* @return
*/
@Override
public int[] getProgress() {
int activeCount = state.getTaskCount();
return new int[] { Math.min(activeCount, quantity), quantity };
}
/**
* Adjust the number of running tasks to better match the target
* by starting or stopping tasks as needed.
*/
@Override
public void adjust() {
int activeCount = state.getTaskCount();
int delta = quantity - activeCount;
if (delta > 0) {
addTasks(delta);
} else if (delta < 0) {
cancelTasks(activeCount);
}
}
/**
* Cancel the requested number of tasks. We exclude any tasks that are already
* in the process of being cancelled. Because we ignore those tasks, it might
* be that we want to reduce the task count, but there is nothing left to cancel.
*
* @param cancelCount
*/
private void cancelTasks(int cancelCount) {
int cancelled = state.getCancelledTaskCount();
int cancellable = cancelCount - cancelled;
int n = cancellable - quantity;
LOG.info("[" + getName( ) + "] - Cancelling " + cancelCount +
" tasks. " + cancelled + " are already cancelled, " +
cancellable + " more will be cancelled.");
if (n <= 0) {
return;
}
for (Task task : state.getStartingTasks()) {
state.cancel(task);
if (--n == 0) {
return;
}
}
for (Task task : state.getActiveTasks()) {
state.cancel(task);
if (--n == 0) {
return;
}
}
// If we get here it means something has gotten out of whack.
LOG.error("Tried to cancel " + cancellable + " tasks, but " + n + " could not be cancelled.");
assert false;
}
/**
* The persistent scheduler has no fixed sequence of tasks to run, it launches
* a set and is never "done". For purposes of completion tracking claim we
* have no further tasks.
*
* @return false
*/
@Override
public boolean hasMoreTasks() { return false; }
@Override
public void requestTimedOut() {
// We requested a node a while back, requested a container from YARN,
// but waited too long to receive it. Most likely cause is that we
// want a container on a node that either does not exist, or is too
// heavily loaded. (That is, we have a 3-node cluster and are requesting
// a 4th node. Or, we have 2 nodes but node 3 has insufficient resources.)
// In either case, we're not likely to ever get the container, so just
// reduce the target size to what we an get.
assert quantity > 0;
if (quantity == 0) {
LOG.error("Container timed out, but target quantity is already 0!");
} else {
quantity--;
LOG.info("Container request timed out. Reducing target container count by 1 to " + quantity);
}
}
}
|
