解决 Net::ZooKeeper找不到动态链接库符号问题

    引用Net::ZooKeeper这个包，可能会报这个错误

Can‘t load ‘/usr/local/lib64/perl5/auto/Net/ZooKeeper/ZooKeeper.so‘ for module Net::ZooKeeper: /usr/local/lib64/perl5/auto/Net/ZooKeeper/ZooKeeper.so: undefined symbol: ZOO_PERM_CREATE at /usr/lib64/perl5/XSLoader.pm line 70.
 at /usr/local/lib64/perl5/Net/ZooKeeper.pm line 109.

    查看XSLoader.pm的70行：

 70     my $libref = dl_load_file($file, 0) or do {
 71         require Carp;
 72         Carp::croak("Can‘t load ‘$file‘ for module $module: " . dl_error());
 73     };

    实际上是加载ZooKeeper.so这个动态链接库。我们objdump，看看这个缺少的符号到底有没有在这个链接库里面。

[zhangbin@localhost xoa2-perl]$ objdump -x /usr/local/lib64/perl5/auto/Net/ZooKeeper/ZooKeeper.so | grep ZOO
0000000000000000         *UND*  0000000000000000              ZOO_PERM_CREATE
0000000000000000         *UND*  0000000000000000              ZOO_READ_ACL_UNSAFE
0000000000000000         *UND*  0000000000000000              ZOO_PERM_WRITE
0000000000000000         *UND*  0000000000000000              ZOO_ASSOCIATING_STATE
0000000000000000         *UND*  0000000000000000              ZOO_CREATED_EVENT
0000000000000000         *UND*  0000000000000000              ZOO_CONNECTED_STATE
0000000000000000         *UND*  0000000000000000              ZOO_AUTH_FAILED_STATE
0000000000000000         *UND*  0000000000000000              ZOO_EPHEMERAL
0000000000000000         *UND*  0000000000000000              ZOO_SEQUENCE
0000000000000000         *UND*  0000000000000000              ZOO_PERM_READ
0000000000000000         *UND*  0000000000000000              ZOO_CREATOR_ALL_ACL
0000000000000000         *UND*  0000000000000000              ZOO_PERM_ALL
0000000000000000         *UND*  0000000000000000              ZOO_DELETED_EVENT
0000000000000000         *UND*  0000000000000000              ZOO_OPEN_ACL_UNSAFE
0000000000000000         *UND*  0000000000000000              ZOO_PERM_ADMIN
0000000000000000         *UND*  0000000000000000              ZOO_CONNECTING_STATE
0000000000000000         *UND*  0000000000000000              ZOO_EXPIRED_SESSION_STATE
0000000000000000         *UND*  0000000000000000              ZOO_NOTWATCHING_EVENT
0000000000000000         *UND*  0000000000000000              ZOO_PERM_DELETE
0000000000000000         *UND*  0000000000000000              ZOO_CHANGED_EVENT
0000000000000000         *UND*  0000000000000000              ZOO_CHILD_EVENT
0000000000000000         *UND*  0000000000000000              ZOO_SESSION_EVENT

    标记为UND，说明这是一个外部符号，应该是需要引用其他库，估计是zookeeper库。但是lib包已经加入了LD_LIBRARY_PATH，非常奇怪。

    尝试重新编译ZooKeeper.so（源码在zookeeper的contrib/zkperl下），发现发布包是用MakeMaker组织的，首先生成Makefile，获得下面的提示：

[zhangbin@localhost zkperl]$ perl Makefile.PL 
Warning (mostly harmless): No library found for -lzookeeper_mt
Generating a Unix-style Makefile
Writing Makefile for Net::ZooKeeper
Writing MYMETA.yml and MYMETA.json

    注意第一行的warning，这是解决问题的关键。Most harmless，but harm this time。查看 Makefile.PL的 第31行

 31 GetOptions(
 32     ‘zookeeper-include=s‘ => \@zk_inc_paths,
 33     ‘zookeeper-lib=s‘ => \@zk_lib_paths
 34 );

   可见第二个选项是必须的。

   重新编译。

[zhangbin@localhost zkperl]$ perl Makefile.PL --zookeeper-lib=/home/zhangbin/env/lib
Checking if your kit is complete...
Looks good
Generating a Unix-style Makefile
Writing Makefile for Net::ZooKeeper
Writing MYMETA.yml and MYMETA.json

   然后make && sudo make install。问题解决。

   可能XSLoader没有自动从LD_LIBRARY_PATH寻找可用的库和符号表的机制。

本文出自 “新青年” 博客，请务必保留此出处http://luckybins.blog.51cto.com/786164/1613660