JVM之編譯OpenJDK

學習JVM時看到書裏講到本身編譯OpenJDK。記錄一下過程

• Mac系統版本：High Sierra 10.13.6
• 源碼版本：jdk8u-dev

1、準備源碼

我是從官網下載網站的，openJDK源碼是用mercurial進行管理的，因此首先使用homebrew安裝mercurial

brew install mercurial

安裝完成以後，再運行命令克隆jdk源碼，以後經過運行腳本get_source.sh獲取全部的源代碼

hg clone http://hg.openjdk.java.net/jdk8u/jdk8u-dev/
cd jdk8u-dev
sh ./get_source.sh 

在獲取源碼的過程當中可能會遇到一些問題，以下所示。我遇到的問題主要是網絡的問題，後來經過切換網絡，使用手機熱點解決了。

abort: stream ended unexpectedly (got 1596 bytes, expected 10164)

2、設置環境變量

在編譯開始以前須要設置一些變量。這裏與書中所講的有一些不同，只由於我用的是Mac平臺，因此編譯器之類的可能會有一些不同。能夠將下面的內容拷貝創建一個腳本運行。

這裏的環境變量設置採用了博客https://www.jianshu.com/p/d9a1e1072f37中的設置

# 語言選項
export LANG=C
# Mac平臺，C編譯器再也不是GCC，是clang
export CC=clang
# 跳過clang的一些嚴格的語法檢查，否則會將N多的警告做爲Error
export COMPILER_WARNINGS_FATAL=false
# 連接時使用的參數
export LFLAGS='-Xlinker -lstdc++'
# 是否使用clang
export USE_CLANG=true
# 使用64位數據模型
export LP64=1
# 告訴編譯平臺是64位，否則會按32位來編譯
export ARCH_DATA_MODEL=64
# 容許自動下載依賴
export ALLOW_DOWNLOADS=true
# 並行編譯的線程數，編譯時間長，爲了避免影響其餘工做，我選擇爲2
export HOTSPOT_BUILD_JOBS=2
# 是否跳過與先前版本的比較
export SKIP_COMPARE_IMAGES=true
# 是否使用預編譯頭文件，加快編譯速度
export USE_PRECOMPILED_HEADER=true
# 是否使用增量編譯
export INCREMENTAL_BUILD=true
# 編譯內容
export BUILD_LANGTOOLS=true
export BUILD_JAXP=true
export BUILD_JAXWS=true
export BUILD_CORBA=true
export BUILD_HOTSPOT=true
export BUILD_JDK=true
# 編譯版本
export SKIP_DEBUG_BUILD=true
export SKIP_FASTDEBUG_BUILD=false
export DEBUG_NAME=debug
# 避開javaws和瀏覽器Java插件之類的部分的build
export BUILD_DEPLOY=false
export BUILD_INSTALL=false
unset JAVA_HOME

3、編譯

設置好環境變量以後，就能夠開始編譯了，首先運行configure，這個腳本會調用不少其餘的腳本進行配置並檢查編譯環境。

bash ./configure

運行成功後的顯示以下：

A new configuration has been successfully created in
/Users/zhengshuangxi/mercurial/temp/build/macosx-x86_64-normal-server-release
using default settings.

Configuration summary:
* Debug level:    release
* JDK variant:    normal
* JVM variants:   server
* OpenJDK target: OS: macosx, CPU architecture: x86, address length: 64

Tools summary:
* Boot JDK:       java version "1.8.0_212" Java(TM) SE Runtime Environment (build 1.8.0_212-b10) Java HotSpot(TM) 64-Bit Server VM (build 25.212-b10, mixed mode)  (at /Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home)
* Toolchain:      gcc (GNU Compiler Collection)
* C Compiler:     Version Apple LLVM version 10.0.0 (clang-1000.11.45.5) Target: x86_64-apple-darwin17.7.0 Thread model: posix InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin (at /usr/bin/clang)
* C++ Compiler:   Version Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1 Apple LLVM version 10.0.0 (clang-1000.11.45.5) Target: x86_64-apple-darwin17.7.0 Thread model: posix InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin (at /usr/bin/g++)

Build performance summary:
* Cores to use:   2
* Memory limit:   8192 MB

也有可能會遇到一些問題，這裏我遇到的問題有：

• Xcode版本不符合，須要Xcode 4
• 沒法找到gcc編譯器

具體解決辦法在本文最後提到。若是沒有遇到問題就能夠進一步編譯了。

直接使用make all命令進行編譯

make all

編譯成功以後顯示以下：

## Finished docs (build time 00:02:31)

----- Build times -------
Start 2019-06-21 16:43:05
End   2019-06-21 16:57:48
00:00:27 corba
00:00:55 demos
00:02:31 docs
00:03:43 hotspot
00:01:34 images
00:00:15 jaxp
00:00:24 jaxws
00:04:10 jdk
00:00:31 langtools
00:00:12 nashorn
00:14:43 TOTAL
-------------------------
Finished building OpenJDK for target 'all'

在編譯過程當中還可能出現一些問題，目前我只遇到這一個問題：

• 參數錯誤「-std=gnu++98」，具體解決辦法在本文最後提到。

4、運行

編譯完成以後，在build文件夾中會生成一個名爲macosx-x86_64-normal-server-release的文件夾，這裏就是咱們編譯生成的結果。在這個文件夾中jdk就是OpenJDK編譯成功的產物。

咱們能夠經過以下命令運行虛擬機，查看版本號，若是沒什麼問題終端會顯示以下信息：

cd ./build/macosx-x86_64-normal-server-release/jdk/bin
./java -version
openjdk version "1.8.0-internal"
OpenJDK Runtime Environment (build 1.8.0-internal-zhengshuangxi_2019_06_21_17_25-b00)
OpenJDK 64-Bit Server VM (build 25.71-b00, mixed mode)

運行以後我又遇到一個問題，在運行過程當中會報錯，提示 libjvm.dylib 動態連接庫相關的錯誤。具體解決在本文最後。

5、遇到的問題及解決辦法

5.一、運行configure以後，提示Xcode版本問題

checking for xcodebuild... /usr/bin/xcodebuild
configure: error: Xcode 4 is required to build JDK 8, the version found was 10.1. Use --with-xcode-path to specify the location of Xcode 4 or make Xcode 4 active by using xcode-select.
configure exiting with result code 1

咱們只須要將文件 jdk8u-dev/common/autoconf/generated-configure.sh 進行一些修改，找到如下代碼並進行註釋，代碼大約在26780行左右。註釋以後就不會提示版本問題了

    # Fail-fast: verify we're building on Xcode 4, we cannot build with Xcode 5 or later
    XCODE_VERSION=`$XCODEBUILD -version | grep '^Xcode ' | sed 's/Xcode //'`
    XC_VERSION_PARTS=( ${XCODE_VERSION//./ } )
    if test ! "${XC_VERSION_PARTS[0]}" = "4"; then
      as_fn_error $? "Xcode 4 is required to build JDK 8, the version found was $XCODE_VERSION. Use --with-xcode-path to specify the location of Xcode 4 or make Xcode 4 active by using xcode-select." "$LINENO" 5
    fi

5.二、gcc編譯器找不到

configure: Will use user supplied compiler CC=clang
checking for clang... /usr/bin/clang
checking resolved symbolic links for CC... no symlink
configure: The C compiler (located as /usr/bin/clang) does not seem to be the required gcc compiler.
configure: The result from running with --version was: ""
configure: error: A gcc compiler is required. Try setting --with-tools-dir.
configure exiting with result code 1

解決辦法也是在generated-configure.sh文件中註釋掉如下的條件代碼。註釋的地方一共有兩處：

# 第一處代碼，27936行左右
  elif test  "x$TOOLCHAIN_TYPE" = xgcc; then
    # gcc --version output typically looks like
    #     gcc (Ubuntu/Linaro 4.8.1-10ubuntu9) 4.8.1
    #     Copyright (C) 2013 Free Software Foundation, Inc.
    #     This is free software; see the source for copying conditions.  There is NO
    #     warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
    COMPILER_VERSION_OUTPUT=`$COMPILER --version 2>&1`
    # Check that this is likely to be GCC.
    $ECHO "$COMPILER_VERSION_OUTPUT" | $GREP "Free Software Foundation" > /dev/null
# 條件語句註釋掉
#     if test $? -ne 0; then
#       { $as_echo "$as_me:${as_lineno-$LINENO}: The $COMPILER_NAME compiler (located as $COMPILER) does not seem to be the required $TOOLCHAIN_TYPE compiler." >&5
# $as_echo "$as_me: The $COMPILER_NAME compiler (located as $COMPILER) does not seem to be the required $TOOLCHAIN_TYPE compiler." >&6;}
#       { $as_echo "$as_me:${as_lineno-$LINENO}: The result from running with --version was: \"$COMPILER_VERSION\"" >&5
# $as_echo "$as_me: The result from running with --version was: \"$COMPILER_VERSION\"" >&6;}
#       as_fn_error $? "A $TOOLCHAIN_TYPE compiler is required. Try setting --with-tools-dir." "$LINENO" 5
#     fi

# 第二處代碼，29677行左右
  elif test  "x$TOOLCHAIN_TYPE" = xgcc; then
    # gcc --version output typically looks like
    #     gcc (Ubuntu/Linaro 4.8.1-10ubuntu9) 4.8.1
    #     Copyright (C) 2013 Free Software Foundation, Inc.
    #     This is free software; see the source for copying conditions.  There is NO
    #     warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
    COMPILER_VERSION_OUTPUT=`$COMPILER --version 2>&1`
    # Check that this is likely to be GCC.
    $ECHO "$COMPILER_VERSION_OUTPUT" | $GREP "Free Software Foundation" > /dev/null
# 條件語句註釋掉
#     if test $? -ne 0; then
#       { $as_echo "$as_me:${as_lineno-$LINENO}: The $COMPILER_NAME compiler (located as $COMPILER) does not seem to be the required $TOOLCHAIN_TYPE compiler." >&5
# $as_echo "$as_me: The $COMPILER_NAME compiler (located as $COMPILER) does not seem to be the required $TOOLCHAIN_TYPE compiler." >&6;}
#       { $as_echo "$as_me:${as_lineno-$LINENO}: The result from running with --version was: \"$COMPILER_VERSION\"" >&5
# $as_echo "$as_me: The result from running with --version was: \"$COMPILER_VERSION\"" >&6;}
#       as_fn_error $? "A $TOOLCHAIN_TYPE compiler is required. Try setting --with-tools-dir." "$LINENO" 5
#     fi

註釋完以後，從新運行configure

5.三、make過程當中遇到參數錯誤「-std=gnu++98」

Making signal interposition lib...
error: invalid argument '-std=gnu++98' not allowed with 'C'
make[6]: *** [libjsig.dylib] Error 1
make[6]: *** Waiting for unfinished jobs....
make[5]: *** [the_vm] Error 2
make[4]: *** [product] Error 2
make[3]: *** [generic_build2] Error 2
make[2]: *** [product] Error 2
make[1]: *** [/Users/zhengshuangxi/mercurial/temp/build/macosx-x86_64-normal-server-release/hotspot/_hotspot.timestamp] Error 2
make: *** [hotspot-only] Error 2

在generated-configure.sh文件中找到參數「-std=gnu++98」，將代碼註釋以下：

      LDFLAGS_JDK="$LDFLAGS_JDK -Wl,-z,relro"
      LEGACY_EXTRA_LDFLAGS="$LEGACY_EXTRA_LDFLAGS -Wl,-z,relro"
    fi
    此處註釋掉
    #CXXSTD_CXXFLAG="-std=gnu++98"

以後從新運行configure，再執行make all

5.四、編譯時遇到 lstdc++ 庫沒法找到

ld: library not found for -lstdc++
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[6]: *** [libsaproc.dylib] Error 1
make[6]: *** Waiting for unfinished jobs....
make[5]: *** [the_vm] Error 2
make[4]: *** [product] Error 2
make[3]: *** [generic_build2] Error 2
make[2]: *** [product] Error 2
make[1]: *** [/Users/zhengshuangxi/mercurial/temp/build/macosx-x86_64-normal-server-release/hotspot/_hotspot.timestamp] Error 2
make: *** [hotspot-only] Error 2

這個緣由是Xcode升級到10之後就沒有包含lstdc++庫了，解決辦法是將/usr/lib中的庫文件拷貝到Xcode相應的文件夾中，並設置相關的軟鏈接。

sudo cp /usr/lib/libstdc++.6.0.9.dylib /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/lib/
cd /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/lib/
sudo ln -s libstdc++.6.0.9.dylib libstdc++.6.dylib
sudo ln -s libstdc++.6.dylib libstdc++.dylib

而後從新運行make all命令進行編譯。

5.五、編譯完成以後，運行虛擬機時出現錯誤

#
# A fatal error has been detected by the Java Runtime Environment:
#
#  SIGILL (0x4) at pc=0x000000010fe801bf, pid=48116, tid=0x0000000000002203
#
# JRE version: OpenJDK Runtime Environment (8.0) (build 1.8.0-internal-zhengshuangxi_2019_06_21_16_42-b00)
# Java VM: OpenJDK 64-Bit Server VM (25.71-b00 mixed mode bsd-amd64 compressed oops)
# Problematic frame:
# V  [libjvm.dylib+0x4801bf]  PerfDataManager::destroy()+0xab
#
# Failed to write core dump. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimited" before starting Java again
#
# An error report file with more information is saved as:
# /Users/zhengshuangxi/mercurial/temp/build/macosx-x86_64-normal-server-release/jdk/bin/hs_err_pid48116.log
#
# If you would like to submit a bug report, please visit:
#   http://bugreport.java.com/bugreport/crash.jsp
#

[error occurred during error reporting , id 0x4]

Abort trap: 6

根據這個錯誤提示，咱們能夠知道錯誤發生在動態連接庫 libjvm.dylib中，根據提示，錯誤代碼時PerDataManager::destroy()函數中。所以咱們須要對這個函數進行修改，即文件 hotspot/src/share/vm/runtime/perfData.cpp，在這個文件中將代碼"delete p"註釋掉。

問題的解決辦法是在博客https://www.jianshu.com/p/34c8a8c37169中看到的。

// 大約在287行
void PerfDataManager::destroy() {

  if (_all == NULL)
    // destroy already called, or initialization never happened
    return;

  for (int index = 0; index < _all->length(); index++) {
    PerfData* p = _all->at(index);
    // 將delete p註釋掉
    //delete p;
  }

  delete(_all);
  delete(_sampled);
  delete(_constants);

  _all = NULL;
  _sampled = NULL;
  _constants = NULL;
}

而後從新運行configure以及make all進行編譯。以後就不會出現問題了。