Hi Kit, 
    Thank you for your quick reply! It is the second, I run "for i in `seq 1 2000`; do curl 3.94.168.82:8080; done”, then only a few responses are back. (the ip is valid, you can try too). 
    I checked the var/log/ directory and I don’t see any problem shown in the log except almost everything is miss.
    I am using an unmodified ATS v8.0.2, so I suspect it is my setting problem, I am testing it on AWS and I have attached my configs below. (I know the value are weird, this is for testing)
Thank you! 

Records.config 
proxy.config.http.insert_response_via_str has changed
Current Value   : 2
Default Value   : 0
proxy.config.http.keep_alive_no_activity_timeout_in has changed
Current Value   : 30000
Default Value   : 120
proxy.config.http.keep_alive_no_activity_timeout_out has changed
Current Value   : 30000
Default Value   : 120
proxy.config.http.cache.required_headers has changed
Current Value   : 0
Default Value   : 2
proxy.config.cache.ram_cache.size has changed
Current Value   : 1288490188
Default Value   : -1
proxy.config.cache.ram_cache_cutoff has changed
Current Value   : 128000
Default Value   : 4194304
proxy.config.url_remap.pristine_host_hdr has changed
Current Value   : 1
Default Value   : 0
proxy.config.net.sock_option_flag_in has changed
Current Value   : 30000
Default Value   : 5
proxy.config.net.sock_option_flag_out has changed
Current Value   : 30000
Default Value   : 1
proxy.config.http.chunking_enabled has changed
Current Value   : 0
Default Value   : 1
proxy.config.http.origin_min_keep_alive_connections has changed
Current Value   : 1
Default Value   : 0
proxy.config.cache.ram_cache.use_seen_filter has changed
Current Value   : 0
Default Value   : 1


Best, 
Jason 


On Feb 27, 2019, at 22:13, Shu Kit Chan <chanshukit@gmail.com> wrote:

By "stall", you mean

1) ATS stops accepting requests altogether ? or
2) One particular request is stalled and the other requests are fine?

If it is the first, I will use gdb to look at the process and see if
there is anything locked or waiting.
If it is the second, I will log the milestones in access log and see
if it can tell where it is stopped. I will also probably turn on debug
messages and see if there's anything going on as well.

Kit

On Wed, Feb 27, 2019 at 7:08 PM Jason Yang <peter.waynechina@gmail.com> wrote:

Hi all,
I have setup a trafficserver and somehow every few transactions, it will stall, what could be wrong and what’s the best way to debug this? Thank you!


Jason