61–70 of 88 posts
Pretty fun puzzle, but this kind of debugging is alien to me. Without going into too much detail, it's pretty easy to see something suspect is going on, and this hunch can be easily tested. This debugging tour takes you to strace, wireshark, all sorts of other low level debugging techniques, when really all you had to do was simulate the client with curl -d and the problem would have been pretty obvious. And in this…
I answered "req.flushHeaders()" but surprisingly it doesn't accept that as a cause, even though the headers would be sent with the initial packet and should improve the latency.
SPOILER ALERT I answered "req.flushHeaders()" but surprisingly it doesn't accept that as a cause, even though the headers would be sent with the initial packet and should improve the latency.
Earlier quoted context omitted.
How would using curl -d make the problem obvious?
It wouldn't have split the request over separate sends. That's what flushHeaders() is doing; it does a separate send for headers vs the body of the request. https://nodejs.org/api/http.html#http_request_flushheaders
``` You said: "strace -p $(ps aux| grep server.py| grep -v "grep"| awk -F ' ' '{print $2}')".
To strace the server, first you need to find its PID. You know that the program is called server.py. ```
Pretty fun puzzle, but this kind of debugging is alien to me. Without going into too much detail, it's pretty easy to see something suspect is going on, and this hunch can be easily tested. This debugging tour takes you to strace, wireshark, all sorts of other low level debugging techniques, when really all you had to do was simulate the client with curl -d and the problem would have been pretty obvious. And in this…
For those of us who grew up reading W.R.Stevens, that might seem absolutely back-to-front. Not only that, curl ain't gonna help you diagnose the next one, which is a Path MTU Discovery issue, or the one after that, which is an undervoltage on the DRAM refresh controller. It might, however, be helpful in nailing that HTTP/2 prefetch request connection upgrade bug.
Mechanical sympathy means feeling every part of the machine, right down in your bones.
Nice, but not perfect: ``` You said: "strace -p $(ps aux| grep server.py| grep -v "grep"| awk -F ' ' '{print $2}')". To strace the server, first you need to find its PID. You know that the program is called server.py. ```
Pretty fun puzzle, but this kind of debugging is alien to me. Without going into too much detail, it's pretty easy to see something suspect is going on, and this hunch can be easily tested. This debugging tour takes you to strace, wireshark, all sorts of other low level debugging techniques, when really all you had to do was simulate the client with curl -d and the problem would have been pretty obvious. And in this…
I had to read this remark a couple of times before I realised it's suggesting a curl debugging trace is somehow more definitive and less complicated than tcpdump, despite it being a TCP issue. For those of us who grew up reading W.R.Stevens, that might seem absolutely back-to-front. Not only that, curl ain't gonna help you diagnose the next one, which is a Path MTU Discovery issue, or the one after that, which is an…