Sahil Takiar created IMPALA-8101: ------------------------------------ Summary: Thrift 11 compilation and Thrift ext-data-source compilation are always run Key: IMPALA-8101 URL: https://issues.apache.org/jira/browse/IMPALA-8101 Project: IMPALA Issue Type: Task Reporter: Sahil Takiar Assignee: Sahil Takiar
[~tarmstrong] pointed out that after IMPALA-7924 the build output started displaying lines such as: "Running thrift 11 compiler on..." even during builds when Thrift files were not modified. I dug a bit deeper and found the following: * This seems to be happening for Thrift compilation of {{ext-data-source}} files as well (e.g. ExternalDataSource.thrift, Types.thrift, etc.); "Running thrift compiler for ext-data-source on..." is always printed * The issue is that the [custom command|https://cmake.org/cmake/help/v3.8/command/add_custom_command.html] for ext-data-source and Thrift 11 compilation specify an {{OUTPUT}} file that does not exist (and is not generated by Thrift) * According to the CMake docs "if the command does not actually create the {{OUTPUT}} then the rule will always run" - so Thrift compilation will run during every build * The issue is that you don't really know what files Thrift is going to generate without actually looking into the Thrift file and understanding Thrift internals * For C++ and Python there is a workaround; for C++ Thrift always generates a file \{THRIFT_FILE_NAME}_types.h (similar situation for Python); however, for Java no such file necessarily exists (ext-data-source only does Java gen) ** This is how regular Thrift compilation works (e.g. compilation of beeswax.thrift, ImpalaService.thrift, etc.); which is why we don't see the issue for regular Thrift compilation A solution for Thrift 11 compilation is to just add generated Python files to the {{OUTPUT}} for the custom_command. A solution for Thrift compilation of ext-data-source seems trickier, so open to suggestions. Ideally, Thrift would be provide a way to return the list of files generated from a .thrift file, without actually generating the files, but I don't see a way to do that. -- This message was sent by Atlassian JIRA (v7.6.3#76005) --------------------------------------------------------------------- To unsubscribe, e-mail: issues-all-unsubscr...@impala.apache.org For additional commands, e-mail: issues-all-h...@impala.apache.org