Native code: configure LDFLAGS and CXXFLAGS to fix the build on systems like
Ubuntu 11.10
-----------------------------------------------------------------------------------------
Key: HADOOP-7979
URL: https://issues.apache.org/jira/browse/HADOOP-7979
Project: Hadoop Common
Issue Type: Bug
Components: build
Affects Versions: 1.0.0, 0.20.203.0, 0.24.0
Environment: Ubuntu 11.10+
Reporter: Michael Noll
I noticed that the build of Hadoop trunk (0.24) and the 1.0/0.20.20x branches
fail on Ubuntu 11.10 when trying to include the native code in the build. The
reason is that the default behavior of {{ld}} was changed in Ubuntu 11.10.
*Background*
>From [Ubuntu 11.10 Release
>Notes|https://wiki.ubuntu.com/OneiricOcelot/ReleaseNotes#GCC_4.6_Toolchain]:
{code}
The compiler passes by default two additional flags to the linker:
[...snipp...]
-Wl,--as-needed with this option the linker will only add a DT_NEEDED tag
for a dynamic library mentioned on the command line if if the library is
actually used.
{code}
This was apparently planned to be changed already back in 11.04 but was
eventually reverted in the final release. From [11.04 Toolchain
Transition|https://wiki.ubuntu.com/NattyNarwhal/ToolchainTransition#Indirect_Linking_for_Shared_Libraries]:
{quote}
Also in Natty, ld runs with the {{\--as-needed}} option enabled by default.
This means that, in the example above, if no symbols from {{libwheel}} were
needed by racetrack, then {{libwheel}} would not be linked even if it was
explicitly included in the command-line compiler flags. NOTE: The ld
{{\--as-needed}} default was reverted for the final natty release, and will be
re-enabled in the o-series.
{quote}
I already run into the same issue with Hadoop-LZO
(https://github.com/kevinweil/hadoop-lzo/issues/33). See the link and the
patch for more details. For Hadoop, the problematic configure script is
{{native/configure}}.
*How to reproduce*
There are two ways to reproduce, depending on the OS you have at hand.
1. Use a stock Ubuntu 11.10 box and run a build that also compiles the native
libs:
{code}
# in the top level directory of the 'hadoop-common' repo,
# i.e. where the BUILDING.txt file resides
$ mvn -Pnative compile
{code}
2. If you do not have Ubuntu 11.10 at hand, simply add {{-Wl,\--as-needed}}
explicitly to {{LDFLAGS}}. This configures {{ld}} to work like Ubuntu 11.10's
default behavior.
*Error message (for trunk/0.24)*
Running the above build command will produce the following output (I added {{-e
-X}} switches to mvn).
{code}
[DEBUG] Executing: /bin/sh -l -c cd
/home/mnoll/programming/git/hadoop/hadoop-common/hadoop-common-project/hadoop-common/target/native
&& make
DESTDIR=/home/mnoll/programming/git/hadoop/hadoop-common/hadoop-common-project/hadoop-common/target/native/target
install
[INFO] /bin/bash ./libtool --tag=CC --mode=compile gcc -DHAVE_CONFIG_H -I.
-I/usr/lib/jvm/default-java/include -I/usr/lib/jvm/default-java/include/linux
-I/home/mnoll/programming/git/hadoop/hadoop-common/hadoop-common-project/hadoop-common/target/native/src
-I/home/mnoll/programming/git/hadoop/hadoop-common/hadoop-common-project/hadoop-common/target/native/javah
-I/usr/local/include -g -Wall -fPIC -O2 -m64 -g -O2 -MT ZlibCompressor.lo -MD
-MP -MF .deps/ZlibCompressor.Tpo -c -o ZlibCompressor.lo `test -f
'src/org/apache/hadoop/io/compress/zlib/ZlibCompressor.c' || echo
'./'`src/org/apache/hadoop/io/compress/zlib/ZlibCompressor.c
[INFO] libtool: compile: gcc -DHAVE_CONFIG_H -I.
-I/usr/lib/jvm/default-java/include -I/usr/lib/jvm/default-java/include/linux
-I/home/mnoll/programming/git/hadoop/hadoop-common/hadoop-common-project/hadoop-common/target/native/src
-I/home/mnoll/programming/git/hadoop/hadoop-common/hadoop-common-project/hadoop-common/target/native/javah
-I/usr/local/include -g -Wall -fPIC -O2 -m64 -g -O2 -MT ZlibCompressor.lo -MD
-MP -MF .deps/ZlibCompressor.Tpo -c
src/org/apache/hadoop/io/compress/zlib/ZlibCompressor.c -fPIC -DPIC -o
.libs/ZlibCompressor.o
[INFO] src/org/apache/hadoop/io/compress/zlib/ZlibCompressor.c: In function
'Java_org_apache_hadoop_io_compress_zlib_ZlibCompressor_initIDs':
[INFO] src/org/apache/hadoop/io/compress/zlib/ZlibCompressor.c:71:41: error:
expected expression before ',' token
[INFO] make: *** [ZlibCompressor.lo] Error 1
{code}
*How to fix*
The fix involves adding proper settings for {{LDFLAGS}} to the build config.
In trunk, this is {{hadoop-common/pom.xml}}. In branches 1.0 and 0.20.20x,
this is {{build.xml}}.
Basically, the fix explicitly adds {{-Wl,\--no-as-needed}} to {{LDFLAGS}}.
Special care must be taken not to add this option when running on Mac OS as its
version of ld does not support this option (and does not need it because by
default it behaves as desired).
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