I am trying to create a custom Minecraft client but first I need to decompile the source files with MCP but it fails. It fails with a JavaOutOfMemoryError. Here is the error:
18:31:41 - Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
18:31:41 - at java.util.Arrays.copyOfRange(Arrays.java:3664)
18:31:41 - at java.lang.String.<init>(String.java:207)
18:31:41 - at java.io.DataInputStream.readUTF(DataInputStream.java:661)
18:31:41 - at java.io.DataInputStream.readUTF(DataInputStream.java:564)
18:31:41 - at org.jetbrains.java.decompiler.struct.consts.ConstantPool.<init>(ConstantPool.java:54)
18:31:41 - at org.jetbrains.java.decompiler.struct.StructClass.<init>(StructClass.java:87)
18:31:41 - at org.jetbrains.java.decompiler.struct.StructClass.<init>(StructClass.java:75)
18:31:41 - at org.jetbrains.java.decompiler.struct.StructContext.addArchive(StructContext.java:167)
18:31:41 - at org.jetbrains.java.decompiler.struct.StructContext.addSpace(StructContext.java:100)
18:31:41 - at org.jetbrains.java.decompiler.struct.StructContext.addSpace(StructContext.java:78)
18:31:41 - at org.jetbrains.java.decompiler.main.Fernflower.addAllClasspath(Fernflower.java:120)
18:31:41 - at org.jetbrains.java.decompiler.main.Fernflower.<init>(Fernflower.java:49)
18:31:41 - at org.jetbrains.java.decompiler.main.decompiler.ConsoleDecompiler.<init>(ConsoleDecompiler.java:126)
18:31:41 - at org.jetbrains.java.decompiler.main.decompiler.ConsoleDecompiler.main(ConsoleDecompiler.java:87)
18:31:41 - '"C:\Program Files\Java\jdk1.8.0_261\bin\java" -jar runtime\bin\fernflower.jar -din=1 -rbr=1 -dgs=1 -asc=1 -rsy=1 -iec=1 -jvn=1 -log=WARN "-e=jars\libraries\net/java/jinput\jinput\2.0.5\jinput-2.0.5.jar" "-e=jars\libraries\org/lwjgl/lwjgl\lwjgl-platform\2.9.4-nightly-20150209\lwjgl-platform-2.9.4-nightly-20150209-natives-windows.jar" "-e=jars\libraries\com/ibm/icu\icu4j-core-mojang\51.2\icu4j-core-mojang-51.2.jar" "-e=jars\libraries\tv/twitch\twitch-external-platform\4.5\twitch-external-platform-4.5-natives-windows-32.jar" "-e=jars\libraries\org/apache/httpcomponents\httpcore\4.3.2\httpcore-4.3.2.jar" "-e=jars\libraries\org/apache/logging/log4j\log4j-api\2.0-beta9\log4j-api-2.0-beta9.jar" "-e=jars\libraries\org/apache/commons\commons-lang3\3.3.2\commons-lang3-3.3.2.jar" "-e=jars\libraries\net/java/dev/jna\jna\3.4.0\jna-3.4.0.jar" "-e=jars\libraries\com/paulscode\libraryjavasound\20101123\libraryjavasound-20101123.jar" "-e=jars\libraries\net/sf/jopt-simple\jopt-simple\4.6\jopt-simple-4.6.jar" "-e=jars\libraries\com/google/guava\guava\17.0\guava-17.0.jar" "-e=jars\libraries\oshi-project\oshi-core\1.1\oshi-core-1.1.jar" "-e=jars\libraries\org/apache/httpcomponents\httpclient\4.3.3\httpclient-4.3.3.jar" "-e=jars\libraries\org/apache/commons\commons-compress\1.8.1\commons-compress-1.8.1.jar" "-e=jars\libraries\net/java/dev/jna\platform\3.4.0\platform-3.4.0.jar" "-e=jars\libraries\com/paulscode\codecjorbis\20101023\codecjorbis-20101023.jar" "-e=jars\libraries\com/paulscode\soundsystem\20120107\soundsystem-20120107.jar" "-e=jars\libraries\com/paulscode\librarylwjglopenal\20100824\librarylwjglopenal-20100824.jar" "-e=jars\libraries\org/lwjgl/lwjgl\lwjgl_util\2.9.4-nightly-20150209\lwjgl_util-2.9.4-nightly-20150209.jar" "-e=jars\libraries\commons-codec\commons-codec\1.9\commons-codec-1.9.jar" "-e=jars\libraries\net/java/jutils\jutils\1.0.0\jutils-1.0.0.jar" "-e=jars\libraries\commons-logging\commons-logging\1.1.3\commons-logging-1.1.3.jar" "-e=jars\libraries\org/lwjgl/lwjgl\lwjgl\2.9.4-nightly-20150209\lwjgl-2.9.4-nightly-20150209.jar" "-e=jars\libraries\commons-io\commons-io\2.4\commons-io-2.4.jar" "-e=jars\libraries\com/mojang\realms\1.7.39\realms-1.7.39.jar" "-e=jars\libraries\com/mojang\authlib\1.5.21\authlib-1.5.21.jar" "-e=jars\libraries\com/google/code/gson\gson\2.2.4\gson-2.2.4.jar" "-e=jars\libraries\com/mojang\netty\1.7.7\netty-1.7.7.jar" "-e=jars\libraries\tv/twitch\twitch\6.5\twitch-6.5.jar" "-e=jars\libraries\com/paulscode\codecwav\20101023\codecwav-20101023.jar" "-e=jars\libraries\tv/twitch\twitch-platform\6.5\twitch-platform-6.5-natives-windows-32.jar" "-e=jars\libraries\net/java/jinput\jinput-platform\2.0.5\jinput-platform-2.0.5-natives-windows.jar" "-e=jars\libraries\org/apache/logging/log4j\log4j-core\2.0-beta9\log4j-core-2.0-beta9.jar" "-e=jars\libraries\io/netty\netty-all\4.0.23.Final\netty-all-4.0.23.Final.jar" temp/minecraft_ff_in.jar temp\src\minecraft' failed : 1
18:31:41 - Decompile failed
I have tried running just the command:
"C:\Program Files\Java\jdk1.8.0_261\bin\java" -jar runtime\bin\fernflower.jar -din=1 -rbr=1 -dgs=1 -asc=1 -rsy=1 -iec=1 -jvn=1 -log=WARN "-e=jars\libraries\net/java/jinput\jinput\2.0.5\jinput-2.0.5.jar" "-e=jars\libraries\org/lwjgl/lwjgl\lwjgl-platform\2.9.4-nightly-20150209\lwjgl-platform-2.9.4-nightly-20150209-natives-windows.jar" "-e=jars\libraries\com/ibm/icu\icu4j-core-mojang\51.2\icu4j-core-mojang-51.2.jar" "-e=jars\libraries\tv/twitch\twitch-external-platform\4.5\twitch-external-platform-4.5-natives-windows-32.jar" "-e=jars\libraries\org/apache/httpcomponents\httpcore\4.3.2\httpcore-4.3.2.jar" "-e=jars\libraries\org/apache/logging/log4j\log4j-api\2.0-beta9\log4j-api-2.0-beta9.jar" "-e=jars\libraries\org/apache/commons\commons-lang3\3.3.2\commons-lang3-3.3.2.jar" "-e=jars\libraries\net/java/dev/jna\jna\3.4.0\jna-3.4.0.jar" "-e=jars\libraries\com/paulscode\libraryjavasound\20101123\libraryjavasound-20101123.jar" "-e=jars\libraries\net/sf/jopt-simple\jopt-simple\4.6\jopt-simple-4.6.jar" "-e=jars\libraries\com/google/guava\guava\17.0\guava-17.0.jar" "-e=jars\libraries\oshi-project\oshi-core\1.1\oshi-core-1.1.jar" "-e=jars\libraries\org/apache/httpcomponents\httpclient\4.3.3\httpclient-4.3.3.jar" "-e=jars\libraries\org/apache/commons\commons-compress\1.8.1\commons-compress-1.8.1.jar" "-e=jars\libraries\net/java/dev/jna\platform\3.4.0\platform-3.4.0.jar" "-e=jars\libraries\com/paulscode\codecjorbis\20101023\codecjorbis-20101023.jar" "-e=jars\libraries\com/paulscode\soundsystem\20120107\soundsystem-20120107.jar" "-e=jars\libraries\com/paulscode\librarylwjglopenal\20100824\librarylwjglopenal-20100824.jar" "-e=jars\libraries\org/lwjgl/lwjgl\lwjgl_util\2.9.4-nightly-20150209\lwjgl_util-2.9.4-nightly-20150209.jar" "-e=jars\libraries\commons-codec\commons-codec\1.9\commons-codec-1.9.jar" "-e=jars\libraries\net/java/jutils\jutils\1.0.0\jutils-1.0.0.jar" "-e=jars\libraries\commons-logging\commons-logging\1.1.3\commons-logging-1.1.3.jar" "-e=jars\libraries\org/lwjgl/lwjgl\lwjgl\2.9.4-nightly-20150209\lwjgl-2.9.4-nightly-20150209.jar" "-e=jars\libraries\commons-io\commons-io\2.4\commons-io-2.4.jar" "-e=jars\libraries\com/mojang\realms\1.7.39\realms-1.7.39.jar" "-e=jars\libraries\com/mojang\authlib\1.5.21\authlib-1.5.21.jar" "-e=jars\libraries\com/google/code/gson\gson\2.2.4\gson-2.2.4.jar" "-e=jars\libraries\com/mojang\netty\1.7.7\netty-1.7.7.jar" "-e=jars\libraries\tv/twitch\twitch\6.5\twitch-6.5.jar" "-e=jars\libraries\com/paulscode\codecwav\20101023\codecwav-20101023.jar" "-e=jars\libraries\tv/twitch\twitch-platform\6.5\twitch-platform-6.5-natives-windows-32.jar" "-e=jars\libraries\net/java/jinput\jinput-platform\2.0.5\jinput-platform-2.0.5-natives-windows.jar" "-e=jars\libraries\org/apache/logging/log4j\log4j-core\2.0-beta9\log4j-core-2.0-beta9.jar" "-e=jars\libraries\io/netty\netty-all\4.0.23.Final\netty-all-4.0.23.Final.jar" temp/minecraft_ff_in.jar temp\src\minecraft
but with an added -Xmx1124m and it works.
I don't know how to reproduce the same while running the decompile.bat file as the file just runs another python file.
I am using MCP 9.18 and trying to decompile Minecraft 1.8.8. My computer has 2GB of memory with 1.9GB being usable.
Go to conf/mcp.cfg. Find this line
CmdFernflower = %s -jar %s -din=1 -rbr=0 -dgs=1 -asc=1 -log=WARN {indir} {outdir}
and change it to this
CmdFernflower = %s -Xmx1.7G -jar %s -din=1 -rbr=0 -dgs=1 -asc=1 -log=WARN {indir} {outdir}
That should give MCP 1.7gb of ram when decompiling. I really recommend to get more ram even 8gb will be a huge help