Java heap space with GSON
eclipse, gson, heap-memory, java
Solution
Instead of tweaking the JVM it might be a good idea to use a streaming API instead of loading the whole json into memory before writing it.
have a look at the 'Mixed Writes Example' on https://sites.google.com/site/gson/streaming
Problem
I'm creating some big JSON file using GSON to create custom JSON from GTFS (Google Transit). The problem is when I'm converting from my object class to JSON: ``` Gson gson = new Gson(); String rutasJSON = gson.toJson(my_object); ``` It gives this exception: ``` Exception in thread "main" java.lang.OutOfMemoryError: Java heap space at java.util.Arrays.copyOf(Unknown Source) at java.lang.AbstractStringBuilder.expandCapacity(Unknown Source) at java.lang.AbstractStringBuilder.ensureCapacityInternal(Unknown Source) at java.lang.AbstractStringBuilder.append(Unknown Source) at java.lang.StringBuffer.append(Unknown Source) at java.io.StringWriter.write(Unknown Source) at com.google.gson.stream.JsonWriter.string(JsonWriter.java:544) at com.google.gson.stream.JsonWriter.writeDeferredName(JsonWriter.java:387) at com.google.gson.stream.JsonWriter.value(JsonWriter.java:402) at com.google.gson.internal.bind.TypeAdapters$13.write(TypeAdapters.java:353) at com.google.gson.internal.bind.TypeAdapters$13.write(TypeAdapters.java:337) at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:68) at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.write(ReflectiveTypeAdapterFactory.java:89) at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.write(ReflectiveTypeAdapterFactory.java:195) at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:68) at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.write(CollectionTypeAdapterFactory.java:96) at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.write(CollectionTypeAdapterFactory.java:60) at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:68) at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.write(ReflectiveTypeAdapterFactory.java:89) at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.write(ReflectiveTypeAdapterFactory.java:195) at com.google.gson.internal.bind.ObjectTypeAdapter.write(ObjectTypeAdapter.java:105) at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:68) at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.write(CollectionTypeAdapterFactory.java:96) at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.write(CollectionTypeAdapterFactory.java:60) at com.google.gson.Gson.toJson(Gson.java:586) at com.google.gson.Gson.toJson(Gson.java:565) at com.google.gson.Gson.toJson(Gson.java:520) at com.google.gson.Gson.toJson(Gson.java:500) at transporte.main(transporte.java:152) ``` I've tried to change eclipse.ini from this: ``` -startup plugins/org.eclipse.equinox.launcher_1.2.0.v20110502.jar --launcher.library plugins/org.eclipse.equinox.launcher.win32.win32.x86_64_1.1.100.v20110502 -product org.eclipse.epp.package.jee.product --launcher.defaultAction openFile --launcher.XXMaxPermSize 256M -showsplash org.eclipse.platform --launcher.XXMaxPermSize 256m --launcher.defaultAction openFile -vmargs -Dosgi.requiredJavaVersion=1.5 -Xms40m -Xmx512m ``` To this: ``` -startup plugins/org.eclipse.equinox.launcher_1.2.0.v20110502.jar --launcher.library plugins/org.eclipse.equinox.launcher.win32.win32.x86_64_1.1.100.v20110502 -product org.eclipse.epp.package.jee.product --launcher.defaultAction openFile --launcher.XXMaxPermSize 1024M -showsplash org.eclipse.platform --launcher.XXMaxPermSize 256m --launcher.defaultAction openFile -vmargs -Dosgi.requiredJavaVersion=1.5 -Xms512m -Xmx512m ``` Any ideas?