Gradle task failed

It would be helpful if you posted the whole log, so I can help pinpoint the error. It does sound like you need to allocate more RAM to MCreator.

   
Executing gradle command: cleanCache clean setupDecompWorkspace --refresh-dependencies
Microsoft Windows [Version 10.0.14393]
(c) 2016 Microsoft Corporation. All rights reserved.
C:\Pylo\MCreator171>cd forge
C:\Pylo\MCreator171\forge>SET "JAVA_HOME=C:\Pylo\MCreator171\jdk32\"
C:\Pylo\MCreator171\forge>SET JAVA_EXE=%JAVA_HOME%\bin\java.exe
C:\Pylo\MCreator171\forge>SET PATH=%JAVA_HOME%\bin\;%PATH%
C:\Pylo\MCreator171\forge>gradlew -Dorg.gradle.jvmargs="-Xms512m -Xmx1024m" cleanCache clean setupDecompWorkspace --refresh-dependencies
To honour the JVM settings for this build a new JVM will be forked. Please consider using the daemon: https://docs.gradle.org/2.14/userguide/gradle_daemon.html.
This mapping 'snapshot_20160518' was designed for MC 1.9.4! Use at your own peril.
#################################################
         ForgeGradle 2.2-SNAPSHOT-f0ba31b        
  https://github.com/MinecraftForge/ForgeGradle  
#################################################
               Powered by MCP unknown               
             http://modcoderpack.com             
         by: Searge, ProfMobius, Fesh0r,         
         R4wk, ZeuX, IngisKahn, bspkrs           
#################################################
:cleanCache
:clean UP-TO-DATE
:deobfCompileDummyTask
:deobfProvidedDummyTask
:getVersionJson
:extractUserdev
:extractDependencyATs SKIPPED
:extractMcpData
:extractMcpMappings
:genSrgs
:downloadClient
:downloadServer
:splitServerJar
:mergeJars
:deobfMcSRG
Applying SpecialSource...
Applying Exceptor...
:decompileMc
Error occurred during initialization of VM
Could not reserve enough space for 3145728KB object heap
:decompileMc FAILED
FAILURE: Build failed with an exception.
* What went wrong:
Execution failed for task ':decompileMc'.
> Process 'command 'C:\Pylo\MCreator171\jdk32\bin\java.exe'' finished with non-zero exit value 1
* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.
BUILD FAILED
Total time: 2 mins 35.831 secs
C:\Pylo\MCreator171\forge>
Task completed with return code 0 in 158094 milliseconds