Ted, yep I'm working from the latest code which includes that unaligned
check, for experimenting I've modified that code to ignore the unaligned
check (just go ahead and say we support it anyway, even though our JDK
returns false: the return value of java.nio.Bits.unaligned()).
My Platform.java for testing contains:
private static final boolean unaligned;
static {
boolean _unaligned;
// use reflection to access unaligned field
try {
System.out.println("Checking unaligned support");
Class<?> bitsClass =
Class.forName("java.nio.Bits", false,
ClassLoader.getSystemClassLoader());
Method unalignedMethod = bitsClass.getDeclaredMethod("unaligned");
unalignedMethod.setAccessible(true);
_unaligned = Boolean.TRUE.equals(unalignedMethod.invoke(null));
System.out.println("Used reflection and _unaligned is: " +
_unaligned);
System.out.println("Setting to true anyway for experimenting");
_unaligned = true;
} catch (Throwable t) {
// We at least know x86 and x64 support unaligned access.
String arch = System.getProperty("os.arch", "");
//noinspection DynamicRegexReplaceableByCompiledPattern
// We don't actually get here since we find the unaligned method OK
and it returns false (I override with true anyway)
// but add s390x incase we somehow fail anyway.
System.out.println("Checking for s390x, os.arch is: " + arch);
_unaligned = arch.matches("^(i[3-6]86|x86(_64)?|x64|s390x|amd64)$");
}
unaligned = _unaligned;
System.out.println("returning: " + unaligned);
}
}
Output is, as you'd expect, "used reflection and _unaligned is false,
setting to true anyway for experimenting", and the tests pass.
No other problems on the platform (pending a different pull request).
Cheers,
From: Ted Yu <[email protected]>
To: Adam Roberts/UK/IBM@IBMGB
Cc: "[email protected]" <[email protected]>
Date: 15/04/2016 15:32
Subject: Re: BytesToBytes and unaligned memory
I assume you tested 2.0 with SPARK-12181 .
Related code from Platform.java if java.nio.Bits#unaligned() throws
exception:
// We at least know x86 and x64 support unaligned access.
String arch = System.getProperty("os.arch", "");
//noinspection DynamicRegexReplaceableByCompiledPattern
_unaligned = arch.matches("^(i[3-6]86|x86(_64)?|x64|amd64)$");
Can you give us some detail on how the code runs for JDKs on zSystems ?
Thanks
On Fri, Apr 15, 2016 at 7:01 AM, Adam Roberts <[email protected]> wrote:
Hi, I'm testing Spark 2.0.0 on various architectures and have a question,
are we sure if
core/src/test/java/org/apache/spark/unsafe/map/AbstractBytesToBytesMapSuite.java
really is attempting to use unaligned memory access (for the
BytesToBytesMapOffHeapSuite tests specifically)?
Our JDKs on zSystems for example return false for the
java.nio.Bits.unaligned() method and yet if I skip this check and add
s390x to the supported architectures (for zSystems), all thirteen tests
here pass.
The 13 tests here all fail as we do not pass the unaligned requirement
(but perhaps incorrectly):
core/src/test/java/org/apache/spark/unsafe/map/BytesToBytesMapOffHeapSuite.java
and I know the unaligned checking is at
common/unsafe/src/main/java/org/apache/spark/unsafe/Platform.java
Either our JDK's method is returning false incorrectly or this test isn't
using unaligned memory access (so the requirement is invalid), there's no
mention of alignment in the test itself.
Any guidance would be very much appreciated, cheers
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IBM United Kingdom Limited - Registered in England and Wales with number
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Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU
Unless stated otherwise above:
IBM United Kingdom Limited - Registered in England and Wales with number
741598.
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU
