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https://issues.apache.org/jira/browse/YARN-11672?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17839590#comment-17839590
]
ASF GitHub Bot commented on YARN-11672:
---------------------------------------
tomicooler commented on code in PR #6734:
URL: https://github.com/apache/hadoop/pull/6734#discussion_r1574502560
##########
hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/java/org/apache/hadoop/yarn/server/nodemanager/containermanager/linux/resources/AbstractCGroupsHandler.java:
##########
@@ -0,0 +1,576 @@
+/*
+ * *
+ * 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.hadoop.yarn.server.nodemanager.containermanager.linux.resources;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FileUtil;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.io.IOUtils;
+import org.apache.hadoop.util.Shell;
+import org.apache.hadoop.yarn.conf.YarnConfiguration;
+import
org.apache.hadoop.yarn.server.nodemanager.containermanager.linux.privileged.PrivilegedOperationExecutor;
+import org.apache.hadoop.yarn.util.Clock;
+import org.apache.hadoop.yarn.util.SystemClock;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.OutputStreamWriter;
+import java.io.PrintWriter;
+import java.io.Writer;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.locks.ReadWriteLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+public abstract class AbstractCGroupsHandler implements CGroupsHandler {
+ private static final Logger LOG =
+ LoggerFactory.getLogger(AbstractCGroupsHandler.class);
+ protected static final String MTAB_FILE = "/proc/mounts";
+
+ private final long deleteCGroupTimeout;
+ private final long deleteCGroupDelay;
+ private final Clock clock;
+
+ protected final String mtabFile;
+ protected final CGroupsMountConfig cGroupsMountConfig;
+ protected final ReadWriteLock rwLock;
+ protected Map<CGroupController, String> controllerPaths;
+ protected Map<String, Set<String>> parsedMtab;
+ protected final PrivilegedOperationExecutor privilegedOperationExecutor;
+ protected final String cGroupPrefix;
+
+ /**
+ * Create cgroup handler object.
+ *
+ * @param conf configuration
+ * @param privilegedOperationExecutor provides mechanisms to execute
+ * PrivilegedContainerOperations
+ * @param mtab mount file location
+ * @throws ResourceHandlerException if initialization failed
+ */
+ AbstractCGroupsHandler(Configuration conf, PrivilegedOperationExecutor
+ privilegedOperationExecutor, String mtab)
+ throws ResourceHandlerException {
+ // Remove leading and trialing slash(es)
+ this.cGroupPrefix = conf.get(YarnConfiguration.
+ NM_LINUX_CONTAINER_CGROUPS_HIERARCHY, "/hadoop-yarn")
+ .replaceAll("^/+", "").replaceAll("/+$", "");
+ this.cGroupsMountConfig = new CGroupsMountConfig(conf);
+ this.deleteCGroupTimeout = conf.getLong(
+ YarnConfiguration.NM_LINUX_CONTAINER_CGROUPS_DELETE_TIMEOUT,
+ YarnConfiguration.DEFAULT_NM_LINUX_CONTAINER_CGROUPS_DELETE_TIMEOUT) +
+ conf.getLong(YarnConfiguration.NM_SLEEP_DELAY_BEFORE_SIGKILL_MS,
+ YarnConfiguration.DEFAULT_NM_SLEEP_DELAY_BEFORE_SIGKILL_MS) + 1000;
+ this.deleteCGroupDelay =
+ conf.getLong(YarnConfiguration.NM_LINUX_CONTAINER_CGROUPS_DELETE_DELAY,
+ YarnConfiguration.DEFAULT_NM_LINUX_CONTAINER_CGROUPS_DELETE_DELAY);
+ this.controllerPaths = new HashMap<>();
+ this.parsedMtab = new HashMap<>();
+ this.rwLock = new ReentrantReadWriteLock();
+ this.privilegedOperationExecutor = privilegedOperationExecutor;
+ this.clock = SystemClock.getInstance();
+ mtabFile = mtab;
+ init();
+ }
+
+ protected void init() throws ResourceHandlerException {
+ initializeControllerPaths();
+ }
+
+ @Override
+ public String getControllerPath(CGroupController controller) {
+ rwLock.readLock().lock();
+ try {
+ return controllerPaths.get(controller);
+ } finally {
+ rwLock.readLock().unlock();
+ }
+ }
+
+ private void initializeControllerPaths() throws ResourceHandlerException {
+ // Cluster admins may have some subsystems mounted in specific locations
+ // We'll attempt to figure out mount points. We do this even if we plan
+ // to mount cgroups into our own tree to control the path permissions or
+ // to mount subsystems that are not mounted previously.
+ // The subsystems for new and existing mount points have to match, and
+ // the same hierarchy will be mounted at each mount point with the same
+ // subsystem set.
+
+ Map<String, Set<String>> newMtab = null;
+ Map<CGroupController, String> cPaths;
+ try {
+ if (this.cGroupsMountConfig.mountDisabledButMountPathDefined()) {
+ newMtab = parsePreConfiguredMountPath();
+ }
+
+ if (newMtab == null) {
+ // parse mtab
+ newMtab = parseMtab(mtabFile);
+ }
+
+ // find cgroup controller paths
+ cPaths = initializeControllerPathsFromMtab(newMtab);
+ } catch (IOException e) {
+ LOG.warn("Failed to initialize controller paths! Exception: " + e);
+ throw new ResourceHandlerException(
+ "Failed to initialize controller paths!");
+ }
+
+ // we want to do a bulk update without the paths changing concurrently
+ rwLock.writeLock().lock();
+ try {
+ controllerPaths = cPaths;
+ parsedMtab = newMtab;
+ } finally {
+ rwLock.writeLock().unlock();
+ }
+ }
+
+ protected abstract Map<String, Set<String>> parsePreConfiguredMountPath()
throws IOException;
+
+ protected Map<CGroupController, String> initializeControllerPathsFromMtab(
+ Map<String, Set<String>> mtab) {
+ Map<CGroupController, String> ret = new HashMap<>();
+
+ for (CGroupController controller : getCGroupControllers()) {
+ String subsystemName = controller.getName();
+ String controllerPath = findControllerInMtab(subsystemName, mtab);
+
+ if (controllerPath != null) {
+ ret.put(controller, controllerPath);
+ }
+ }
+ return ret;
+ }
+
+ protected abstract List<CGroupController> getCGroupControllers();
+
+ /* We are looking for entries of the form:
+ * none /cgroup/path/mem cgroup rw,memory 0 0
+ *
+ * Use a simple pattern that splits on the five spaces, and
+ * grabs the 2, 3, and 4th fields.
+ */
+
+ private static final Pattern MTAB_FILE_FORMAT = Pattern.compile(
+ "^[^\\s]+\\s([^\\s]+)\\s([^\\s]+)\\s([^\\s]+)\\s[^\\s]+\\s[^\\s]+$");
+
+ /*
+ * Returns a map: path -> mount options
+ * for mounts with type "cgroup". Cgroup controllers will
+ * appear in the list of options for a path.
+ */
+ protected Map<String, Set<String>> parseMtab(String mtab)
+ throws IOException {
+ Map<String, Set<String>> ret = new HashMap<>();
+ BufferedReader in = null;
+
+ try {
+ FileInputStream fis = new FileInputStream(mtab);
+ in = new BufferedReader(new InputStreamReader(fis,
StandardCharsets.UTF_8));
+
+ for (String str = in.readLine(); str != null;
+ str = in.readLine()) {
+ Matcher m = MTAB_FILE_FORMAT.matcher(str);
+ boolean mat = m.find();
+ if (mat) {
+ String path = m.group(1);
+ String type = m.group(2);
+ String options = m.group(3);
+
+ Set<String> controllerSet = handleMtabEntry(path, type, options);
+ if (controllerSet != null) {
+ ret.put(path, controllerSet);
+ }
+ }
+ }
+ } catch (IOException e) {
+ if (Shell.LINUX) {
+ throw new IOException("Error while reading " + mtab, e);
+ } else {
+ // Ignore the error, if we are running on an os other than Linux
+ LOG.warn("Error while reading " + mtab, e);
+ }
+ } finally {
+ IOUtils.cleanupWithLogger(LOG, in);
+ }
+
+ return ret;
+ }
+
+ protected abstract Set<String> handleMtabEntry(String path, String type,
String options)
+ throws IOException;
+
+ /**
+ * Find the hierarchy of the subsystem.
+ * The kernel ensures that a subsystem can only be part of a single
hierarchy.
+ * The subsystem can be part of multiple mount points, if they belong to the
+ * same hierarchy.
+ *
+ * @param controller subsystem like cpu, cpuset, etc...
+ * @param entries map of paths to mount options
+ * @return the first mount path that has the requested subsystem
+ */
+ protected String findControllerInMtab(String controller,
+ Map<String, Set<String>> entries) {
+ for (Map.Entry<String, Set<String>> e : entries.entrySet()) {
+ if (e.getValue().contains(controller)) {
+ if (new File(e.getKey()).canRead()) {
+ return e.getKey();
+ } else {
+ LOG.warn(String.format(
+ "Skipping inaccessible cgroup mount point %s", e.getKey()));
+ }
+ }
+ }
+
+ return null;
+ }
+
+ protected abstract void mountCGroupController(CGroupController controller)
+ throws ResourceHandlerException;
+
+ @Override
+ public String getRelativePathForCGroup(String cGroupId) {
+ return cGroupPrefix + Path.SEPARATOR + cGroupId;
+ }
+
+ @Override
+ public String getPathForCGroup(CGroupController controller, String cGroupId)
{
+ return getControllerPath(controller) + Path.SEPARATOR + cGroupPrefix
+ + Path.SEPARATOR + cGroupId;
+ }
+
+ @Override
+ public String getPathForCGroupTasks(CGroupController controller,
+ String cGroupId) {
+ return getPathForCGroup(controller, cGroupId)
+ + Path.SEPARATOR + CGROUP_PROCS_FILE;
+ }
+
+ @Override
+ public String getPathForCGroupParam(CGroupController controller,
+ String cGroupId, String param) {
+ return getPathForCGroup(controller, cGroupId)
+ + Path.SEPARATOR + controller.getName()
+ + "." + param;
+ }
+
+ /**
+ * Mount cgroup or use existing mount point based on configuration.
+ *
+ * @param controller - the controller being initialized
+ * @throws ResourceHandlerException yarn hierarchy cannot be created or
+ * accessed for any reason
+ */
+ @Override
+ public void initializeCGroupController(CGroupController controller) throws
+ ResourceHandlerException {
+ if (this.cGroupsMountConfig.isMountEnabled() &&
+ cGroupsMountConfig.ensureMountPathIsDefined()) {
+ // We have a controller that needs to be mounted
+ mountCGroupController(controller);
+ }
+
+ // We are working with a pre-mounted contoller
+ // Make sure that YARN cgroup hierarchy path exists
+ initializePreMountedCGroupController(controller);
+ }
+
+ /**
+ * This function is called when the administrator opted
+ * to use a pre-mounted cgroup controller.
+ * There are two options.
+ * 1. YARN hierarchy already exists. We verify, whether we have write access
+ * in this case.
+ * 2. YARN hierarchy does not exist, yet. We create it in this case. If
cgroup v2 is used
+ * an additional step is required to update the cgroup.subtree_control file,
see
+ * {@link CGroupsV2HandlerImpl#updateEnabledControllersInHierarchy}
+ *
+ * @param controller the controller being initialized
+ * @throws ResourceHandlerException yarn hierarchy cannot be created or
+ * accessed for any reason
+ */
+ private void initializePreMountedCGroupController(CGroupController
controller)
+ throws ResourceHandlerException {
+ // Check permissions to cgroup hierarchy and
+ // create YARN cgroup if it does not exist, yet
+ String controllerPath = getControllerPath(controller);
+
+ if (controllerPath == null) {
+ throw new ResourceHandlerException(
+ String.format("Controller %s not mounted."
+ + " You either need to mount it with %s"
+ + " or mount cgroups before launching Yarn",
+ controller.getName(), YarnConfiguration.
+ NM_LINUX_CONTAINER_CGROUPS_MOUNT));
+ }
+
+ File rootHierarchy = new File(controllerPath);
+ File yarnHierarchy = new File(rootHierarchy, cGroupPrefix);
+ String subsystemName = controller.getName();
+
+ LOG.info("Initializing mounted controller " + controller.getName() + " " +
+ "at " + yarnHierarchy);
+
+ if (!rootHierarchy.exists()) {
+ throw new ResourceHandlerException(getErrorWithDetails(
+ "Cgroups mount point does not exist or not accessible",
+ subsystemName,
+ rootHierarchy.getAbsolutePath()
+ ));
+ } else if (!yarnHierarchy.exists()) {
+ LOG.info("Yarn control group does not exist. Creating " +
+ yarnHierarchy.getAbsolutePath());
+ try {
+ if (!yarnHierarchy.mkdir()) {
+ // Unexpected: we just checked that it was missing
+ throw new ResourceHandlerException(getErrorWithDetails(
+ "Unexpected: Cannot create yarn cgroup",
+ subsystemName,
+ yarnHierarchy.getAbsolutePath()
+ ));
+ }
+ } catch (SecurityException e) {
+ throw new ResourceHandlerException(getErrorWithDetails(
+ "No permissions to create yarn cgroup",
+ subsystemName,
+ yarnHierarchy.getAbsolutePath()
+ ), e);
+ }
+ } else if (!FileUtil.canWrite(yarnHierarchy)) {
+ throw new ResourceHandlerException(getErrorWithDetails(
+ "Yarn control group not writable",
+ subsystemName,
+ yarnHierarchy.getAbsolutePath()
+ ));
+ }
+
+ try {
+ updateEnabledControllersInHierarchy(yarnHierarchy);
Review Comment:
We have a chain of `ResourceHandler`(s) (`cpu`, `io`, ...) and the
`.boostrap()` is called on each of them, where they call the
`initializeCGroupController` with the actual controller (e.g. `cpu`) which then
ends up here. But for cgroup v2 we initialise all valid cgroupv2 controller
**at once** regardless of the configuration.
```
private static void initializeConfiguredResourceHandlerChain(
Configuration conf, Context nmContext)
throws ResourceHandlerException {
ArrayList<ResourceHandler> handlerList = new ArrayList<>();
addHandlerIfNotNull(handlerList,
initNetworkResourceHandler(conf));
addHandlerIfNotNull(handlerList,
initDiskResourceHandler(conf));
addHandlerIfNotNull(handlerList,
initMemoryResourceHandler(conf));
addHandlerIfNotNull(handlerList,
initCGroupsCpuResourceHandler(conf));
addHandlerIfNotNull(handlerList, getNumaResourceHandler(conf,
nmContext));
addHandlersFromConfiguredResourcePlugins(handlerList, conf, nmContext);
resourceHandlerChain = new ResourceHandlerChain(handlerList);
}
```
Shouldn't the `updateEnabledControllersInHierarchy` be called only for a
valid cgroupv2 controller and only enable that controller (if it is not already
enabled)?
```
if (controller.isInV2()) {
updateEnabledControllersInHierarchy(yarnHierarchy, controller);
}
```
Since this is an abstract class, the if shouldn't really be here but in the
v2 implementation. This is just an example.
> Create a CgroupHandler implementation for cgroup v2
> ---------------------------------------------------
>
> Key: YARN-11672
> URL: https://issues.apache.org/jira/browse/YARN-11672
> Project: Hadoop YARN
> Issue Type: Sub-task
> Reporter: Benjamin Teke
> Assignee: Benjamin Teke
> Priority: Major
> Labels: pull-request-available
>
> [CGroupsHandler's|https://github.com/apache/hadoop/blob/69b328943edf2f61c8fc139934420e3f10bf3813/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/java/org/apache/hadoop/yarn/server/nodemanager/containermanager/linux/resources/CGroupsHandler.java#L36]
> current implementation holds the functionality to mount and setup the YARN
> specific cgroup v1 functionality. A similar v2 implementation should be
> created that allows initialising the v2 structure.
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