[IMPALA-12535] Wrong unit of thread duration shown in the json result of /thread-group?all&json URL

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: Impala 4.4.0
• Component/s: Backend
• Epic Color: ghx-label-2
• Assignee: Quanlong Huang
• Reporter: Quanlong Huang
• Created: 02/Nov/23 02:05
• Updated: 22/Jan/24 12:52
• Resolved: 22/Jan/24 12:52

Description

Impalad returns the JSON results of thread statistics for URL "/thread-group?all&json", e.g. for a thread:

{
  name: "StatestoreSubscriber-0",
  id: 43136,
  user_ns: 26.94,
  kernel_ns: 10.18,
  iowait_ns: 0.01
},

However, the unit is not ns. Instead, it's seconds. The html page shows the correct unit.

Looking into the code, we actually divided the duration by 1e9 so the unit should be second.

        val.AddMember("user_ns", static_cast<double>(stats.user_ns) / 1e9,
            document->GetAllocator());
        val.AddMember("kernel_ns", static_cast<double>(stats.kernel_ns) / 1e9,
            document->GetAllocator());
        val.AddMember("iowait_ns", static_cast<double>(stats.iowait_ns) / 1e9,
            document->GetAllocator());

https://github.com/apache/impala/blob/39adf42a30765208e51e970339e950aae8544848/be/src/util/thread.cc#L283-L288