HBase 0.94 master启动过程源码分析

HBase 0.94 master启动过程源码分析

周海汉
http://abloz.com
[zhouhh@Hadoop48 bin]$ pwd

/home/zhouhh/hbase-0.94.0/bin

[zhouhh@Hadoop48 bin]$ vi hbase

shell中开始准备java和hadoop，hbase的环境，然后处理传入的参数。如果参数是”master”，则类是org.apache.hadoop.hbase.master.HMaster

270 elif [ "$COMMAND" = "master" ] ; then

271 CLASS=’org.apache.hadoop.hbase.master.HMaster’

272 if [ "$1" != "stop" ] ; then

273 HBASE_OPTS=”$HBASE_OPTS $HBASE_MASTER_OPTS”

274 fi

275 elif [ "$COMMAND" = "regionserver" ] ; then

276 CLASS=’org.apache.hadoop.hbase.regionserver.HRegionServer’

277 if [ "$1" != "stop" ] ; then

278 HBASE_OPTS=”$HBASE_OPTS $HBASE_REGIONSERVER_OPTS”

279 fi

280 elif [ "$COMMAND" = "thrift" ] ; then

281 CLASS=’org.apache.hadoop.hbase.thrift.ThriftServer’

282 if [ "$1" != "stop" ] ; then

283 HBASE_OPTS=”$HBASE_OPTS $HBASE_THRIFT_OPTS”

284 fi

328 # Exec unless HBASE_NOEXEC is set.

执行程序，简化一下就是java HMaster “$@”

329 if [ "${HBASE_NOEXEC}" != "" ]; then

330 “$J***A” -XX:OnOutOfMemoryError=”kill -9 %p” $J***A_HEAP_MAX $HBASE_OPTS -classpath “$CLASSPATH” $CLASS “$@”

331 else

332 exec “$J***A” -XX:OnOutOfMemoryError=”kill -9 %p” $J***A_HEAP_MAX $HBASE_OPTS -classpath “$CLASSPATH” $CLASS “$@”

333 fi

[zhouhh@Hadoop48 master]$ pwd

/home/zhouhh/hbase-0.94.0/src/main/java/org/apache/hadoop/hbase/master

hbase shell脚本会调用到HMaster.java的main(),该函数执行HMasterCommandLine的doMain(),并将HMaster作为参数传入。最终调用到HMaster的父类HasThread.start(),然后调用到HMaster.run(),becomeActiveMaster(),抢先向Zookeeper注册成Master，启动完毕

[zhouhh@Hadoop48 master]$ vi HMaster.java

这是HMaster 源代码入口

1752 public static void main(String [] args) throws Exception {

1753 VersionInfo.logVersion();

1754 new HMasterCommandLine(HMaster.class).doMain(args);

1755 }

HMasterCommandLine的doMain会调用到其父类ServerCommandLine的doMain，ServerCommandLine又是Tool接口的子类，实现了run函数，

[zhouhh@Hadoop48 master]$ vi HMasterCommandLine.java

44 public class HMasterCommandLine extends ServerCommandLine {

66 public int run(String args[]) throws Exception {

94 List remainingArgs = cmd.getArgList();

72 CommandLine cmd;

74 cmd = new GnuParser().parse(opt, args);

100 String command = remainingArgs.get(0);

101

start 参数，调用startMaster()函数

102 if (“start”.equals(command)) {

103 return startMaster();

104 } else if (“stop”.equals(command)) {

105 return stopMaster();

106 } else {

107 usage(“Invalid command: ” + command);

108 return -1;

109 }

110 }

112 private int startMaster() {

113 Configuration conf = getConf();

114 try {

115 // If ‘local’, defer to LocalHBaseCluster instance. Starts master

116 // and regionserver both in the one JVM.

117 if (LocalHBaseCluster.isLocal(conf)) {

启动本地HBase的HMaster

118 final MiniZooKeeperCluster zooKeeperCluster =

119 new MiniZooKeeperCluster();

120 File zkDataPath = new File(conf.get(HConstants.ZOOKEEPER_DATA_DIR));

121 int zkClientPort = conf.getInt(HConstants.ZOOKEEPER_CLIENT_PORT, 0);

122 if (zkClientPort == 0) {

123 throw new IOException(“No config value for ”

124 + HConstants.ZOOKEEPER_CLIENT_PORT);

125 }

126 zooKeeperCluster.setDefaultClientPort(zkClientPort);

127 int clientPort = zooKeeperCluster.startup(zkDataPath);

128 if (clientPort != zkClientPort) {

129 String errorMsg = “Could not start ZK at requested port of ” +

130 zkClientPort + “. ZK was started at port: ” + clientPort +

131 “. Aborting as clients (e.g. shell) will not be able to find ” +

132 “this ZK quorum.”;

133 System.err.println(errorMsg);

134 throw new IOException(errorMsg);

135 }

136 conf.set(HConstants.ZOOKEEPER_CLIENT_PORT,

137 Integer.toString(clientPort));

138 // Need to have the zk cluster shutdown when master is shutdown.

139 // Run a subclass that does the zk cluster shutdown on its way out.

140 LocalHBaseCluster cluster = new LocalHBaseCluster(conf, 1, 1,

141 LocalHMaster.class, HRegionServer.class);

142 ((LocalHMaster)cluster.getMaster(0)).setZKCluster(zooKeeperCluster);

143 cluster.startup();

144 waitOnMasterThreads(cluster);

145 } else {

启动分布式HBase master，masterClass正是传入的HMaster.java的HMaster类，所以会调用到HMaster.start();

146 HMaster master = HMaster.constructMaster(masterClass, conf);

147 if (master.isStopped()) {

148 LOG.info(“Won’t bring the Master up as a shutdown is requested”);

149 return -1;

150 }

151 master.start();

152 master.join();

153 if(master.isAborted())

154 throw new RuntimeException(“HMaster Aborted”);

155 }

156 } catch (Throwable t) {

157 LOG.error(“Failed to start master”, t);

158 return -1;

159 }

160 return 0;

161 }

234 }

[zhouhh@Hadoop48 util]$ pwd

/home/zhouhh/hbase-0.94.0/src/main/java/org/apache/hadoop/hbase/util

[zhouhh@Hadoop48 util]$ vi ServerCommandLine.java

33 /**

34 * Base class for command lines that start up various HBase daemons.

35 */

36 public abstract class ServerCommandLine extends Configured implements Tool {

doMain函数调用ToolRunner.run,因将自身传入ToolRunner，ToolRunner.run会调用所传入的Tool的run函数，即实现在ServerCommandLine子类HMasterCommandLine的run函数，从而调用到HMasterCommandLine.startMaster

75 public void doMain(String args[]) throws Exception {

76 int ret = ToolRunner.run(

77 HBaseConfiguration.create(), this, args);

78 if (ret != 0) {

79 System.exit(ret);

80 }

81 }

82 }

[zhouhh@Hadoop48 util]$ pwd

/home/zhouhh/hadoop-1.0.3/src/core/org/apache/hadoop/util

[zhouhh@Hadoop48 util]$ vi ToolRunner.java

ToolRunner 作用，提供一个分析参数和配置，并调用Tool.run的接口

39 public class ToolRunner {

54 public static int run(Configuration conf, Tool tool, String[] args)

55 throws Exception{

59 GenericOptionsParser parser = new GenericOptionsParser(conf, args);

60 //set the configuration back, so that Tool can configure itself

61 tool.setConf(conf);

62

63 //get the args w/o generic hadoop args

64 String[] toolArgs = parser.getRemainingArgs();

65 return tool.run(toolArgs);

66 }

[zhouhh@Hadoop48 util]$ vi Tool.java

Tool 提供统一run接口

70 public interface Tool extends Configurable {

78 int run(String [] args) throws Exception;

79 }