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Improving error message when flock is not available #3699

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frsyuki opened this Issue Feb 25, 2016 · 1 comment

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frsyuki commented Feb 25, 2016

Overview:

  • we got flock unsupported or native support failed to load error.
  • it was difficult to debug the cause until we find -Xnative.verbose=true option from JRuby source code.
  • it's helpful if error message shows a way to debug the cause.
  • actual the cause was that /tmp was mounted with noexec option.

Details

Installing a gem failed with this error:

$ embulk gem install embulk-input-jdbc
2016-02-19 18:45:43.698 -0600: Embulk v0.8.5
Fetching: embulk-input-jdbc-0.6.4.gem (100%)
NotImplementedError: flock unsupported or native support failed to load
                       flock at org/jruby/RubyFile.java:304
  block in cache_update_path at uri:classloader:/META-INF/jruby.home/lib/ruby/stdlib/rubygems/remote_fetcher.rb:316
                        open at org/jruby/RubyIO.java:1125
                        open at org/jruby/RubyKernel.java:310
           cache_update_path at uri:classloader:/META-INF/jruby.home/lib/ruby/stdlib/rubygems/remote_fetcher.rb:315
                    download at uri:classloader:/META-INF/jruby.home/lib/ruby/stdlib/rubygems/remote_fetcher.rb:174
                    download at uri:classloader:/META-INF/jruby.home/lib/ruby/stdlib/rubygems/source.rb:210
                    download at uri:classloader:/META-INF/jruby.home/lib/ruby/stdlib/rubygems/resolver/activation_request.rb:60
            block in install at uri:classloader:/META-INF/jruby.home/lib/ruby/stdlib/rubygems/request_set.rb:160
                        each at org/jruby/RubyArray.java:1560
                     install at uri:classloader:/META-INF/jruby.home/lib/ruby/stdlib/rubygems/request_set.rb:150
                 install_gem at uri:classloader:/META-INF/jruby.home/lib/ruby/stdlib/rubygems/commands/install_command.rb:249
       block in install_gems at uri:classloader:/META-INF/jruby.home/lib/ruby/stdlib/rubygems/commands/install_command.rb:299
                        each at org/jruby/RubyArray.java:1560
                install_gems at uri:classloader:/META-INF/jruby.home/lib/ruby/stdlib/rubygems/commands/install_command.rb:295
                     execute at uri:classloader:/META-INF/jruby.home/lib/ruby/stdlib/rubygems/commands/install_command.rb:202
      invoke_with_build_args at uri:classloader:/META-INF/jruby.home/lib/ruby/stdlib/rubygems/command.rb:307
                process_args at uri:classloader:/META-INF/jruby.home/lib/ruby/stdlib/rubygems/command_manager.rb:168
                         run at uri:classloader:/META-INF/jruby.home/lib/ruby/stdlib/rubygems/command_manager.rb:138
                         run at uri:classloader:/META-INF/jruby.home/lib/ruby/stdlib/rubygems/gem_runner.rb:54
                         run at /home/sneisius/.embulk/bin/embulk!/embulk/command/embulk_run.rb:165
                       <top> at /home/sneisius/.embulk/bin/embulk!/embulk/command/embulk_main.rb:2
                     require at org/jruby/RubyKernel.java:939
                      (root) at uri:classloader:/META-INF/jruby.home/lib/ruby/stdlib/rubygems/core_ext/kernel_require.rb:1
                       <top> at file:/home/sneisius/.embulk/bin/embulk!/embulk/command/embulk_bundle.rb:51```

After digging into the source code, we found that the error happens when jruby works with jnr-posix. Then, we found -Xnative.verbose=true option that shows stacktrace. Here is the full stacktrace:
https://gist.github.com/frsyuki/d762149c43315361fe19

This error possibly happens when /tmp is mounted with noexec, or execution on /tmp is prohibited by SELinux. But it was hard for us to come to this conclusion because error message doesn't suggest how to debug the cause of the failure when it loads a native library.

It would be good if the error message suggests how to debug the cause. For example:

diff --git a/core/src/main/java/org/jruby/ext/JRubyPOSIXHandler.java b/core/src/main/java/org/jruby/ext/JRubyPOSIXHandler.java
index 5c249f4..2689b7d 100644
--- a/core/src/main/java/org/jruby/ext/JRubyPOSIXHandler.java
+++ b/core/src/main/java/org/jruby/ext/JRubyPOSIXHandler.java
@@ -48,7 +48,7 @@ public class JRubyPOSIXHandler implements POSIXHandler {
     }

     public void unimplementedError(String method) {
-        throw runtime.newNotImplementedError(method + " unsupported or native support failed to load");
+        throw runtime.newNotImplementedError(method + " unsupported or native support failed to load. Set _JAVA_OPTIONS=-Djruby.native.verbose=true environment variable to debug");
     }

     public void warn(WARNING_ID id, String message, Object... data) {

I used _JAVA_OPTIONS here so that the suggestion is valid even if jruby is used as a library.

Some issues might have been easier to solve with this message: #3266 #3285 #3409

Environment

  • JRuby 9.0.4.0
  • RedHat Enterprise Linux 7

@headius headius added this to the JRuby 9.1.0.0 milestone Mar 9, 2016

@kares kares added the enhancement label Mar 11, 2016

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headius Apr 19, 2016

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I've added a page for gathering info about native library problems in JRuby here: http://wiki.jruby.org/Native-Libraries. I will add this to relevant error messages.

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headius commented Apr 19, 2016

I've added a page for gathering info about native library problems in JRuby here: http://wiki.jruby.org/Native-Libraries. I will add this to relevant error messages.

@headius headius closed this in 2edf7a1 Apr 19, 2016

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