Failed to get pattern path

[minimAluminiumalism]

Describe the bug

Missing pattern path causes incomplete span name.

Environment

• OS: Linux/arm64
• Go Version: go1.23.1
• Version: latest

To Reproduce

Let's see the example rolldice you've provided.

When I running the example in docker container using docker compose up, everything is ok, and I can see the full span name on the jaeger web page, which like the picture 2 I've provided above.

But when I instrument an application on the same host, the span doesn't have any pattern name which only consists of http method.

I checked carefully and only found the running environment is different.

Expected behavior

Full span name with http method and pattern path

Additional context

In fact, you can check the demo picture http_Db_traces.jpg in example/httpPlusdb/, the span name is also incompleted.

Maybe here is the code that causes the problem in internal/pkg/instrumentation/bpf/net/http/server/bpf/probe.bpf.c (I cannot ensure that, but I found pat_ptr is sometimes 0 so it won't execute read_go_string())

if (pattern_path_supported) {
        void *pat_ptr = NULL;
        bpf_probe_read(&pat_ptr, sizeof(pat_ptr), (void *)(req_ptr + req_pat_pos));
        if (pat_ptr != NULL) {
            read_go_string(pat_ptr, pat_str_pos, http_server_span->path_pattern, sizeof(http_server_span->path), "patterned path from Request");
        }
    }

[minimAluminiumalism]

#896 Maybe this question is similar to it?

[MrAlias]

I'm not able to reproduce this. Running the rolldice example results in the same span names as the example.

https://github.com/open-telemetry/opentelemetry-go-instrumentation/blob/main/examples/rolldice/images/jaeger_trace.png

Are you still able to reproduce the failure? Can you provide code that will reproduce the issue?