Hadoop 动态调整日志级别
hadoop线上基础服务DataNode，线上排查问题，直接重启服务调整日志级别代价太大，耗时长，hadoop给我们提供了动态修改类日志级别的方式。可以指定某个类调整，调整这个类在某个DataNode的日志级别。
需要先根据报错定位到哪个DataNode，再通过日志定位到报错的类，知道该类的哪个方法的逻辑有问题，然后调整这个DN的这个类的日志级别。因此要对hadoop代码相对熟悉
修改方式
打开DataNode的Web UI，选择Log Level
进入后，在第一个框输入类名，点击“Get Log Level”可以查看当前该类的日志等级
在第二个框输入类名，填写要设置的日志等级，点击“Set Log Level”，即可设置成功。
源码实现
实现一个servelet，调用相关log实现的代码，关键代码如下：
Log log = LogFactory.getLog(logName);
log.setLevel(org.apache.log4j.Level.toLevel(level));完整代码
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package org.apache.hadoop.log;
import java.io.*;
import java.net.*;
import java.util.regex.Pattern;
import javax.servlet.*;
import javax.servlet.http.*;
import com.google.common.base.Charsets;
import org.apache.commons.logging.*;
import org.apache.commons.logging.impl.*;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.http.HttpServer2;
import org.apache.hadoop.util.ServletUtil;
/**
* Change log level in runtime.
*/
@InterfaceStability.Evolving
public class LogLevel {
public static final String USAGES = "\nUsage: General options are:\n"
+ "\t[-getlevel <host:httpPort> <name>]\n"
+ "\t[-setlevel <host:httpPort> <name> <level>]\n";
/**
* A command line implementation
*/
public static void main(String[] args) {
if (args.length == 3 && "-getlevel".equals(args[0])) {
process("http://" + args[1] + "/logLevel?log=" + args[2]);
return;
}
else if (args.length == 4 && "-setlevel".equals(args[0])) {
process("http://" + args[1] + "/logLevel?log=" + args[2]
+ "&level=" + args[3]);
return;
}
System.err.println(USAGES);
System.exit(-1);
}
private static void process(String urlstring) {
try {
URL url = new URL(urlstring);
System.out.println("Connecting to " + url);
URLConnection connection = url.openConnection();
connection.connect();
BufferedReader in = new BufferedReader(new InputStreamReader(
connection.getInputStream(), Charsets.UTF_8));
for(String line; (line = in.readLine()) != null; )
if (line.startsWith(MARKER)) {
System.out.println(TAG.matcher(line).replaceAll(""));
}
in.close();
} catch (IOException ioe) {
System.err.println("" + ioe);
}
}
static final String MARKER = "<!-- OUTPUT -->";
static final Pattern TAG = Pattern.compile("<[^>]*>");
/**
* A servlet implementation
*/
@InterfaceAudience.LimitedPrivate({"HDFS", "MapReduce"})
@InterfaceStability.Unstable
public static class Servlet extends HttpServlet {
private static final long serialVersionUID = 1L;
@Override
public void doGet(HttpServletRequest request, HttpServletResponse response
) throws ServletException, IOException {
// If user is a static user and auth Type is null, that means
// there is a non-security environment and no need authorization,
// otherwise, do the authorization.
final ServletContext servletContext = getServletContext();
if (!HttpServer2.isStaticUserAndNoneAuthType(servletContext, request) &&
!HttpServer2.hasAdministratorAccess(servletContext,
request, response)) {
return;
}
PrintWriter out = ServletUtil.initHTML(response, "Log Level");
String logName = ServletUtil.getParameter(request, "log");
String level = ServletUtil.getParameter(request, "level");
if (logName != null) {
out.println("<br /><hr /><h3>Results</h3>");
out.println(MARKER
+ "Submitted Log Name: <b>" + logName + "</b><br />");
Log log = LogFactory.getLog(logName);
out.println(MARKER
+ "Log Class: <b>" + log.getClass().getName() +"</b><br />");
if (level != null) {
out.println(MARKER + "Submitted Level: <b>" + level + "</b><br />");
}
if (log instanceof Log4JLogger) {
process(((Log4JLogger)log).getLogger(), level, out);
}
else if (log instanceof Jdk14Logger) {
process(((Jdk14Logger)log).getLogger(), level, out);
}
else {
out.println("Sorry, " + log.getClass() + " not supported.<br />");
}
}
out.println(FORMS);
out.println(ServletUtil.HTML_TAIL);
}
static final String FORMS = "\n<br /><hr /><h3>Get / Set</h3>"
+ "\n<form>Log: <input type='text' size='50' name='log' /> "
+ "<input type='submit' value='Get Log Level' />"
+ "</form>"
+ "\n<form>Log: <input type='text' size='50' name='log' /> "
+ "Level: <input type='text' name='level' /> "
+ "<input type='submit' value='Set Log Level' />"
+ "</form>";
private static void process(org.apache.log4j.Logger log, String level,
PrintWriter out) throws IOException {
if (level != null) {
if (!level.equalsIgnoreCase(org.apache.log4j.Level.toLevel(level)
.toString())) {
out.println(MARKER + "Bad Level : <b>" + level + "</b><br />");
} else {
log.setLevel(org.apache.log4j.Level.toLevel(level));
out.println(MARKER + "Setting Level to " + level + " ...<br />");
}
}
out.println(MARKER
+ "Effective Level: <b>" + log.getEffectiveLevel() + "</b><br />");
}
private static void process(java.util.logging.Logger log, String level,
PrintWriter out) throws IOException {
if (level != null) {
String levelToUpperCase = level.toUpperCase();
try {
log.setLevel(java.util.logging.Level.parse(levelToUpperCase));
} catch (IllegalArgumentException e) {
out.println(MARKER + "Bad Level : <b>" + level + "</b><br />");
}
out.println(MARKER + "Setting Level to " + level + " ...<br />");
}
java.util.logging.Level lev;
for(; (lev = log.getLevel()) == null; log = log.getParent());
out.println(MARKER + "Effective Level: <b>" + lev + "</b><br />");
}
}
}
log框架设置日志级别的方式
#Log4j2
LoggerContext loggerContext = (LoggerContext) LogManager.getContext(false);
LoggerConfig loggerConfig = loggerContext.getConfiguration().getLoggers().get("root");
loggerConfig.setLevel(level);
#Logback
LoggerContext loggerContext = (LoggerContext) LoggerFactory.getILoggerFactory();
Logger logger = loggerContext.getLogger("root");
((ch.qos.logback.classic.Logger) logger).setLevel(level);
#Java Util Logging
Logger logger = Logger.getLogger("root");
logger.setLevel(level);
