用btrace分析线上服务

部署

• btrace1.2.5.1已经部署到集群
  • /home/xjyin/btrace-1.2.5.1

使用方式

• 基本使用方式

    sh /btrace-1.2.5.1/bin/btrace <pid>  <your .java btrace class>
  

实战

• 动态观察指定进程中所有产生throwable(包括被吞掉的exception)的逻辑（打出stacktrace）

    sh ~/xjyin/btrace-1.2.5.1/bin/btrace <pid>  ~/xjyin/btrace-1.2.5.1/myClasses/OnThrow.java > exception.log
  

• OnThrow.java类内容如下

    /*
     * Copyright 2008-2010 Sun Microsystems, Inc.  All Rights Reserved.
     * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
     *
     * This code is free software; you can redistribute it and/or modify it
     * under the terms of the GNU General Public License version 2 only, as
     * published by the Free Software Foundation.  Sun designates this
     * particular file as subject to the "Classpath" exception as provided
     * by Sun in the LICENSE file that accompanied this code.
     *
     * This code is distributed in the hope that it will be useful, but WITHOUT
     * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
     * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
     * version 2 for more details (a copy is included in the LICENSE file that
     * accompanied this code).
     *
     * You should have received a copy of the GNU General Public License version
     * 2 along with this work; if not, write to the Free Software Foundation,
     * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
     *
     * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
     * CA 95054 USA or visit www.sun.com if you need additional information or
     * have any questions.
     */
  
    package lisn;
  
    import com.sun.btrace.annotations.*;
    import static com.sun.btrace.BTraceUtils.*;
  
    /**
     * This example demonstrates printing stack trace
     * of an exception and thread local variables. This
     * trace script prints exception stack trace whenever
     * java.lang.Throwable's constructor returns. This way
     * you can trace all exceptions that may be caught and
     * "eaten" silently by the traced program. Note that the
     * assumption is that the exceptions are thrown soon after
     * creation [like in "throw new FooException();"] rather
     * that be stored and thrown later.
     */
    @BTrace public class OnThrow {
        // store current exception in a thread local
        // variable (@TLS annotation). Note that we can't
        // store it in a global variable!
        @TLS static Throwable currentException;
  
        // introduce probe into every constructor of java.lang.Throwable
        // class and store "this" in the thread local variable.
        @OnMethod(
            clazz="java.lang.Throwable",
            method="<init>"
        )
        public static void onthrow(@Self Throwable self) {
            currentException = self;
        }
  
        @OnMethod(
            clazz="java.lang.Throwable",
            method="<init>"
        )
        public static void onthrow1(@Self Throwable self, String s) {
            currentException = self;
        }
  
        @OnMethod(
            clazz="java.lang.Throwable",
            method="<init>"
        )
        public static void onthrow1(@Self Throwable self, String s, Throwable cause) {
            currentException = self;
        }
  
        @OnMethod(
            clazz="java.lang.Throwable",
            method="<init>"
        )
        public static void onthrow2(@Self Throwable self, Throwable cause) {
            currentException = self;
        }
  
        // when any constructor of java.lang.Throwable returns
        // print the currentException's stack trace.
        @OnMethod(
            clazz="java.lang.Throwable",
            method="<init>",
            location=@Location(Kind.RETURN)
        )
        public static void onthrowreturn() {
            if (currentException != null) {
                Threads.jstack(currentException);
                println("=====================");
                currentException = null;
            }
        }
    }
  

• 更多例子见 ~/xjyin/btrace-1.2.5.1/samples/