Tag Archives: diagnose

scala的诊断方法(4) -Ytyper-debug 编译项

Posted on by
Reply

在定位之前的那个问题时，发现了-Ytyper-debug选项，可以吧编译器在typer阶段的一些信息打印出来，比-Xprint:typer多出一些类型推导的信息：

$ cat A.scala
object A {
    println(1,2,3)
}

$ scalac -Ytyper-debug  A.scala
|-- <empty> EXPRmode-POLYmode-QUALmode (site: package <root>)
|    \-> <empty>.type
|-- object A BYVALmode-EXPRmode (site: package <empty>)
|    |-- super EXPRmode-POLYmode-QUALmode (silent: <init> in A)
|    |    |-- this EXPRmode (silent: <init> in A)
|    |    |    \-> A.type
|    |    \-> A.type
|    |-- println(1, 2, 3) BYVALmode-EXPRmode (site: value <local A> in A)
|    |    |-- println BYVALmode-EXPRmode-FUNmode-POLYmode (silent: value <local A> in A)
|    |    |    \-> (x: Any)Unit <and> ()Unit
|    |    |-- scala.Tuple3(1, 2, 3) : pt=Any BYVALmode-EXPRmode (silent: value <local A> in A)
|    |    |    |-- scala.Tuple3 BYVALmode-EXPRmode-FUNmode-POLYmode (silent: value <local A> in A)
|    |    |    |    |-- scala.Tuple3.apply BYVALmode-EXPRmode-FUNmode-POLYmode (silent: value <local A> in A)
|    |    |    |    |    [adapt] [T1, T2, T3](_1: T1, _2: T2, _3: T3)(T1, T2, T3) adapted to [T1, T2, T3](_1: T1, _2: T2, _3: T3)(T1, T2, T3)
|    |    |    |    |    \-> (_1: T1, _2: T2, _3: T3)(T1, T2, T3)
|    |    |    |    [adapt] Tuple3.type adapted to [T1, T2, T3](_1: T1, _2: T2, _3: T3)(T1, T2, T3)
|    |    |    |    \-> (_1: T1, _2: T2, _3: T3)(T1, T2, T3)
|    |    |    |-- 1 BYVALmode-EXPRmode-POLYmode (silent: value <local A> in A)
|    |    |    |    \-> Int(1)
|    |    |    |-- 2 BYVALmode-EXPRmode-POLYmode (silent: value <local A> in A)
|    |    |    |    \-> Int(2)
|    |    |    |-- 3 BYVALmode-EXPRmode-POLYmode (silent: value <local A> in A)
|    |    |    |    \-> Int(3)
|    |    |    solving for (T1: ?T1, T2: ?T2, T3: ?T3)
|    |    |    \-> (Int, Int, Int)
|    |    \-> Unit
|    \-> [object A] A.type
|-- (_1: <?>, _2: <?>, _3: <?>)(T1, T2, T3) EXPRmode-FUNmode-POLYmode-TAPPmode (site: object A) implicits disabled
|    |-- new (Int, Int, Int) EXPRmode-POLYmode-QUALmode (site: object A) implicits disabled
|    |    \-> (Int, Int, Int)
|    \-> (_1: Int, _2: Int, _3: Int)(Int, Int, Int)

在解析的时候，对println(1,2,3)里的参数执行了Tuple3(1,2,3)最终参数识别成了Tuple3[Int,Int,Int]类型。暂没发现更大的价值，先记下来以后再补充。

检测最耗cpu的线程的脚本

Posted on by
3

这个脚本用于定位出当前java进程里最耗cpu的那个线程，给出cpu的占用率和当前堆栈信息。这个脚本仅限于linux上，我没有找到在mac下定位线程使用cpu情况的工具，如果你知道请告诉我一下。

先模拟一个耗cpu的java进程，启动一个scala的repl并在上面跑一段死循环：

scala> while(true) {}

脚本执行效果：

$ ./busythread.sh `pidof java`
tid: 431  cpu: %98.8
"main" prio=10 tid=0x00007f777800a000 nid=0x1af runnable [0x00007f7781c2e000]
    java.lang.Thread.State: RUNNABLE
    at $line3.$read$$iw$$iw$.<init>(<console>:8)
    at $line3.$read$$iw$$iw$.<clinit>(<console>)
    at $line3.$eval$.$print$lzycompute(<console>:7)
    - locked <0x00000000fc201758> (a $line3.$eval$)
    at $line3.$eval$.$print(<console>:6)
    at $line3.$eval.$print(<console>)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at scala.tools.nsc.interpreter.IMain$ReadEvalPrint.call(IMain.scala:739)
    at scala.tools.nsc.interpreter.IMain$Request.loadAndRun(IMain.scala:986)
    at scala.tools.nsc.interpreter.IMain$WrappedRequest$$anonfun$loadAndRunReq$1.apply(IMain.scala:593)
    at scala.tools.nsc.interpreter.IMain$WrappedRequest$$anonfun$loadAndRunReq$1.apply(IMain.scala:592)
    at scala.reflect.internal.util.ScalaClassLoader$class.asContext(ScalaClassLoader.scala:31)
    at scala.reflect.internal.util.AbstractFileClassLoader.asContext(AbstractFileClassLoader.scala:19)
    at scala.tools.nsc.interpreter.IMain$WrappedRequest.loadAndRunReq(IMain.scala:592)
    at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:524)
    at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:520)

脚本内容：

#!/bin/bash

if [ $# -eq 0 ];then
    echo "please enter java pid"
    exit -1
fi

pid=$1
jstack_cmd=""

if [[ $JAVA_HOME != "" ]]; then
    jstack_cmd="$JAVA_HOME/bin/jstack"
else
    r=`which jstack 2>/dev/null`
    if [[ $r != "" ]]; then
        jstack_cmd=$r
    else
        echo "can not find jstack"
        exit -2
    fi
fi

#line=`top -H  -o %CPU -b -n 1  -p $pid | sed '1,/^$/d' | grep -v $pid | awk 'NR==2'`

line=`top -H -b -n 1 -p $pid | sed '1,/^$/d' | sed '1d;/^$/d' | grep -v $pid | sort -nrk9 | head -1`
echo "$line" | awk '{print "tid: "$1," cpu: %"$9}'
tid_0x=`printf "%0x" $(echo "$line" | awk '{print $1}')`
$jstack_cmd $pid | grep $tid_0x -A20 | sed -n '1,/^$/p'

脚本已放到服务器上，可以通过下面的方式执行：

$ bash <(curl -s https://hongjiang.info/busythread.sh)  java_pid

update: 感谢容若的反馈，很多环境的procps版本较低，top还不支持-o参数，排序那块用sort解决了，脚本已更新。

lsof查看进程在使用的已删除的文件

Posted on by
Reply

有时会遇到这种情况，当一个进程正在向一个文件写数据时，该文件的目录可能被移动，或该文件已被其他进程删除。
用 lsof +L1 可以查看那些在访问的已被删除的文件

lsof +L1 shows you all open files that have a link count less than 1, often indicative of a cracker trying to hide something

hongjiang@whj ~ % sudo lsof +L1
COMMAND   PID  USER   FD   TYPE DEVICE SIZE/OFF NLINK    NODE NAME
mysqld  22070 mysql    4u   REG  202,1        0     0 1048935 /tmp/ibfwFj0I (deleted)
mysqld  22070 mysql    5u   REG  202,1        0     0 1048937 /tmp/ibpUnKvR (deleted)
mysqld  22070 mysql    6u   REG  202,1        0     0 1048942 /tmp/ibXYbb1Z (deleted)

这个参数不好记，也可以用 lsof -n | grep deleted 来查看。

scala的诊断方法(3) 在repl下统计方法的执行时间

Posted on by
3

为了方便启动repl时自动加载，把这段函数定义放在.scalarc文件中：

hongjiang@whj-mbp ~ % cat .scalarc

def time[T](code : => T) =  {
    val t0 = System.nanoTime : Double
    val res = code
    val t1 = System.nanoTime : Double
    println("Elapsed time " + (t1 - t0) / 1000000.0 + " msecs")
    res
}

把scala命令alias一下，每次启动时自动load启动脚本：

alias scala='scala -deprecation -feature -i ~/.scalarc'

用time方法测试执行时间

// 测试代码块的执行时间
scala> time{ var sum=0; for(i<-0 to 1000000) sum=sum+i; println(sum) }
    1784293664
    Elapsed time 71.57888 msecs

scala> def fib(n:Int):Int = if (n<2)  n else fib(n-1) + fib(n-2);

// 测试方法的执行时间  
scala> time( fib(40) )
    Elapsed time 407.36 msecs
    res3: Int = 102334155