Ruby C擴展：rb_funcall導致段錯誤

Question

我的擴展程序使用Ruby庫通過接口發送和接收命令和遙測數據包，並將它們提供給C文件傳輸庫進行處理。

收到大量數據包后，我將收到此段錯誤。 這是來自GDB的回溯。

            #0  search_method (defined_class_ptr=<synthetic pointer>, id=6177, klass=<optimized out>) at vm_method.c:567
            #1  rb_method_entry_get_without_cache (klass=19934160, id=6177, defined_class_ptr=0x12c5500) at vm_method.c:592
            #2  0x00007ffff7aced90 in rb_method_entry (klass=klass@entry=19934160, id=<optimized out>, 
                defined_class_ptr=defined_class_ptr@entry=0x12c5500) at vm_method.c:663
            #3  0x00007ffff7acee71 in vm_search_method (ci=ci@entry=0x12c54c0, recv=<optimized out>) at vm_insnhelper.c:842
            #4  0x00007ffff7ad4b3d in vm_exec_core (th=th@entry=0x6035d0, initial=initial@entry=0) at insns.def:1068
            #5  0x00007ffff7ad951b in vm_exec (th=th@entry=0x6035d0) at vm.c:1440
            #6  0x00007ffff7adac91 in vm_call0_body (th=th@entry=0x6035d0, ci=ci@entry=0x7fffffffbcb0, argv=0x7fffffffbd60)
                at vm_eval.c:180
            #7  0x00007ffff7adb6c6 in vm_call0 (defined_class=<optimized out>, me=<optimized out>, argv=<optimized out>, 
                argc=1, id=14481, recv=22956880, th=0x6035d0) at vm_eval.c:59
            #8  rb_call0 (recv=recv@entry=22956880, mid=14481, argc=argc@entry=1, argv=argv@entry=0x7fffffffbd60, 
                scope=scope@entry=CALL_FCALL, self=<optimized out>) at vm_eval.c:349
            #9  0x00007ffff7adbc64 in rb_call (scope=CALL_FCALL, argv=0x7fffffffbd60, argc=1, mid=<optimized out>, 
                recv=22956880) at vm_eval.c:616
            #10 rb_funcall (recv=recv@entry=22956880, mid=<optimized out>, n=n@entry=1) at vm_eval.c:818
            #11 0x00007ffff6092b10 in DL_RecvPdu () at CFGroundClient.c:414
            #12 0x00007ffff6092dbe in method_run (self=<optimized out>) at CFGroundClient.c:302
            #13 0x00007ffff7ace272 in vm_call_cfunc_with_frame (ci=0x0, reg_cfp=0x7ffff7fd1f70, th=0x6035d0)
                at vm_insnhelper.c:1380
            #14 vm_call_cfunc (th=th@entry=0x6035d0, reg_cfp=reg_cfp@entry=0x7ffff7fd1f70, ci=ci@entry=0xa29090)
                at vm_insnhelper.c:1473
            #15 0x00007ffff7ae0f6e in vm_call_method (th=0x6035d0, cfp=0x7ffff7fd1f70, ci=0xa29090) at vm_insnhelper.c:1689
            #16 0x00007ffff7ad4b4b in vm_exec_core (th=th@entry=0x6035d0, initial=initial@entry=0) at insns.def:1069
            #17 0x00007ffff7ad951b in vm_exec (th=th@entry=0x6035d0) at vm.c:1440
            #18 0x00007ffff7adaa73 in rb_iseq_eval_main (iseqval=iseqval@entry=10626960) at vm.c:1685
            #19 0x00007ffff798707d in ruby_exec_internal (n=0xa22790) at eval.c:254
            #20 0x00007ffff798948d in ruby_exec_node (n=n@entry=0xa22790) at eval.c:319
            #21 0x00007ffff798bc3e in ruby_run_node (n=0xa22790) at eval.c:311
            #22 0x000000000040087b in main (argc=3, argv=0x7fffffffde58) at main.c:36

以下是相關代碼：

                void DL_RecvPdu() {
                       .....
                    /* Segfault coming from here 
                       CUR_PACKET.read("PDU_DATA"); 
                       Reads telemetry item PDU_DATA from packet CUR_PACKET
                       and returns results. PDU data is an array of bytes 
                       represented as a Ruby string that can contain nulls */
                    VALUE pdu_data_block = rb_funcall(rb_CUR_PACKET, 
                        rb_READ, 1, 
                        rb_PDU_DATA
                    );
                        ....
                }

有誰知道此錯誤可能來自何處以及如何解決？

Answer 1

有很多可能的原因導致此問題，但數據不足（似乎）。

一種解釋可能是Ruby對象（即rb_CUR_PACKET ， rb_READ或rb_PDU_DATA ）在您調用該函數時無效，因為它們可能已由GC（垃圾收集器）收集了。

如果Ruby對象未引用這些對象，則它們的內存可能比您預期的要早釋放。

一個簡單的解決方案是將對象注冊為全局對象（它們將永遠不會被釋放）或將它們分配為用戶對象內部的變量。

另一個可能的原因是您沒有在GIL（全局指令鎖）內執行代碼。

Ruby MRI代碼必須始終在GIL和Ruby線程中運行。 如果您離開了GIL或生成了不是Ruby線程的新線程，那么幸運的話，您的代碼將崩潰。

我懷疑是GC，但這是一個折騰。

祝好運！