This is really an issue. I could work on a pull request for better control of Unsafe usage together with a new setting "jvm.use.unsafe" (or something) which should be true by default and auto-detectable, so ES could run OOTB also on other JVMs or big endian platforms.
Jörg On Tue, Jul 22, 2014 at 11:43 AM, David Roberts <[email protected] > wrote: > Hello, > > After upgrading from Elasticsearch 1.0.1 to 1.2.2 I'm getting JVM core > dumps on Solaris 10 on SPARC. > > # A fatal error has been detected by the Java Runtime Environment: > # > # SIGBUS (0xa) at pc=0xffffffff7e452d78, pid=15483, tid=263 > # > # JRE version: Java(TM) SE Runtime Environment (7.0_55-b13) (build > 1.7.0_55-b13) > # Java VM: Java HotSpot(TM) 64-Bit Server VM (24.55-b03 mixed mode > solaris-sparc compressed oops) > # Problematic frame: > # V [libjvm.so+0xc52d78] Unsafe_GetLong+0x158 > > I'm pretty sure the problem here is that Elasticsearch is making > increasing use of "unsafe" functions in Java, presumably to speed things > up, and some CPUs are more picky than others about memory alignment. In > particular, x86 will tolerate misaligned memory access whereas SPARC won't. > > Somebody has tried to report this to Oracle in the past and > (understandably) Oracle has said that if you're going to use unsafe > functions you need to understand what you're doing: > http://bugs.java.com/bugdatabase/view_bug.do?bug_id=8021574 > > A quick grep through the code of the two versions of Elasticsearch shows > that the new use of "unsafe" memory access functions is in the > BytesReference, MurmurHash3 and HyperLogLogPlusPlus classes: > > bash-3.2$ git checkout v1.0.1 > Checking out files: 100% (2904/2904), done. > > bash-3.2$ find . -name '*.java' | xargs grep UnsafeUtils > ./src/main/java/org/elasticsearch/common/util/UnsafeUtils.java:public enum > UnsafeUtils { > ./src/main/java/org/elasticsearch/search/aggregations/bucket/BytesRefHash.java: > if (id == -1L || UnsafeUtils.equals(key, get(id, spare))) { > ./src/main/java/org/elasticsearch/search/aggregations/bucket/BytesRefHash.java: > } else if (UnsafeUtils.equals(key, get(curId, spare))) { > ./src/test/java/org/elasticsearch/benchmark/common/util/BytesRefComparisonsBenchmark.java:import > org.elasticsearch.common.util.UnsafeUtils; > ./src/test/java/org/elasticsearch/benchmark/common/util/BytesRefComparisonsBenchmark.java: > return UnsafeUtils.equals(b1, b2); > > bash-3.2$ git checkout v1.2.2 > Checking out files: 100% (2220/2220), done. > > bash-3.2$ find . -name '*.java' | xargs grep UnsafeUtils > ./src/main/java/org/elasticsearch/common/bytes/BytesReference.java:import > org.elasticsearch.common.util.UnsafeUtils; > ./src/main/java/org/elasticsearch/common/bytes/BytesReference.java: > return UnsafeUtils.equals(a.array(), a.arrayOffset(), b.array(), > b.arrayOffset(), a.length()); > ./src/main/java/org/elasticsearch/common/hash/MurmurHash3.java:import > org.elasticsearch.common.util.UnsafeUtils; > ./src/main/java/org/elasticsearch/common/hash/MurmurHash3.java: > return UnsafeUtils.readLongLE(key, blockOffset); > ./src/main/java/org/elasticsearch/common/hash/MurmurHash3.java: > long k1 = UnsafeUtils.readLongLE(key, i); > ./src/main/java/org/elasticsearch/common/hash/MurmurHash3.java: > long k2 = UnsafeUtils.readLongLE(key, i + 8); > ./src/main/java/org/elasticsearch/common/util/BytesRefHash.java: > if (id == -1L || UnsafeUtils.equals(key, get(id, spare))) { > ./src/main/java/org/elasticsearch/common/util/BytesRefHash.java: > } else if (UnsafeUtils.equals(key, get(curId, spare))) { > ./src/main/java/org/elasticsearch/common/util/UnsafeUtils.java:public enum > UnsafeUtils { > ./src/main/java/org/elasticsearch/search/aggregations/metrics/cardinality/HyperLogLogPlusPlus.java:import > org.elasticsearch.common.util.UnsafeUtils; > ./src/main/java/org/elasticsearch/search/aggregations/metrics/cardinality/HyperLogLogPlusPlus.java: > return UnsafeUtils.readIntLE(readSpare.bytes, readSpare.offset); > ./src/test/java/org/elasticsearch/benchmark/common/util/BytesRefComparisonsBenchmark.java:import > org.elasticsearch.common.util.UnsafeUtils; > ./src/test/java/org/elasticsearch/benchmark/common/util/BytesRefComparisonsBenchmark.java: > return UnsafeUtils.equals(b1, b2); > > Presumably one of these three new uses is what is causing the JVM SIGBUS > error I'm seeing. > > A quick look at the MurmurHash3 class shows that the hash128 method > accepts an arbitrary offset and passes it to an unsafe function with no > check that it's a multiple of 8: > > public static Hash128 hash128(byte[] key, int offset, int length, long > seed, Hash128 hash) { > long h1 = seed; > long h2 = seed; > > if (length >= 16) { > > final int len16 = length & 0xFFFFFFF0; // higher multiple of > 16 that is lower than or equal to length > final int end = offset + len16; > for (int i = offset; i < end; i += 16) { > long k1 = UnsafeUtils.readLongLE(key, i); > long k2 = UnsafeUtils.readLongLE(key, i + 8); > > This is a recipe for generating JVM core dumps on architectures such as > SPARC, Itanium and PowerPC that don't support unaligned 64 bit memory > access. > > Does Elasticsearch have any policy for support of hardware other than > x86? If not, I don't think many people would care but you really ought to > clearly say so on your platform support page. If you do intend to support > non-x86 architectures then you need to be much more careful about the use > of unsafe memory accesses. > > Regards, > > David > > -- > You received this message because you are subscribed to the Google Groups > "elasticsearch" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/elasticsearch/e57c7412-4878-4cd5-b21f-72b4d39e98f1%40googlegroups.com > <https://groups.google.com/d/msgid/elasticsearch/e57c7412-4878-4cd5-b21f-72b4d39e98f1%40googlegroups.com?utm_medium=email&utm_source=footer> > . > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. 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