Thank you, Alexander. That, at least, explains the problem. And what should be the workaround if the combined set of data is larger than 2 GB?
On Fri, Aug 22, 2014 at 1:50 PM, Alexander Pivovarov <apivova...@gmail.com> wrote: > Max array size is max integer. So, byte array can not be bigger than 2GB > On Aug 22, 2014 1:41 PM, "Yuriy" <yuriythe...@gmail.com> wrote: > >> Hadoop Writable interface relies on "public void write(DataOutput out)" >> method. >> It looks like behind DataOutput interface, Hadoop uses DataOutputStream, >> which uses a simple array under the cover. >> >> When I try to write a lot of data in DataOutput in my reducer, I get: >> >> Caused by: java.lang.OutOfMemoryError: Requested array size exceeds VM >> limit at java.util.Arrays.copyOf(Arrays.java:3230) at >> java.io.ByteArrayOutputStream.grow(ByteArrayOutputStream.java:113) at >> java.io.ByteArrayOutputStream.ensureCapacity(ByteArrayOutputStream.java:93) >> at java.io.ByteArrayOutputStream.write(ByteArrayOutputStream.java:140) at >> java.io.DataOutputStream.write(DataOutputStream.java:107) at >> java.io.FilterOutputStream.write(FilterOutputStream.java:97) >> >> Looks like the system is unable to allocate the continuous array of the >> requested size. Apparently, increasing the heap size available to the >> reducer does not help - it is already at 84GB (-Xmx84G) >> >> If I cannot reduce the size of the object that I need to serialize (as >> the reducer constructs this object by combining the object data), what >> should I try to work around this problem? >> >> Thanks, >> >> Yuriy >> >
