I'm evaluating k6 for my load testing needs. I've set up a basic load test and I'm currently trying to interpret the error messages and result values I get. Maybe someone can help me interpret what I'm seeing:
If I crank up the VUS to about 300, I start seeing error messages in the console and at 500 lots of error messages.
These mostly consist of:
dial tcp XXX:443: i/o timeout
read tcp YYY(local ip):35252->XXX(host ip):443: read: connection reset by peer
level=warning msg="Request Failed" error="unexpected EOF"
Get https://REQUEST_URL/: context deadline exceeded"
I also have problems with several checks:
check errors in which res.status === 0 and res.body === null
check errors in which res.status === 0, but the body contains the correct content
How can res.status be 0 but the body still contains the proper values?
I suspect that I'm reaching the connection limit of my load producing machine and that's why I get the error messages. So I'd have to set up a cluster or move to the Cloud runners!?
The stats generated by k6 show long http_req_blocked values, which I interpret as the time waiting to get a connection port. This seems to indicate that the connection pool of my test running machine is at its limits.
http_req_blocked...........: avg=5.66s min=0s med=3.26s max=59.38s p(90)=13.12s p(95)=20.31s
http_req_connecting........: avg=1.85s min=0s med=280.16ms max=24.27s p(90)=4.2s p(95)=9.24s
http_req_duration..........: avg=2.05s min=0s med=496.24ms max=1m0s p(90)=4.7s p(95)=8.39s
http_req_receiving.........: avg=600.94ms min=0s med=82.89µs max=58.8s p(90)=436.95ms p(95)=2.67s
http_req_sending...........: avg=1.42ms min=0s med=35.8µs max=11.76s p(90)=56.22µs p(95)=62.45µs
http_req_tls_handshaking...: avg=3.85s min=0s med=1.78s max=58.49s p(90)=8.93s p(95)=15.81s
http_req_waiting...........: avg=1.45s min=0s med=399.43ms max=1m0s p(90)=3.23s p(95)=5.87s
Can anyone help me out interpret the results I'm seeing?
You are likely running out of CPU on the runner.
As explained in the http specific metrics of the documentation, you are right about http_req_blocked it is (mostly) the time from when we say we want to make a
request to when we get a socket on which to do it. This is most likely because:
the test runner is running out of CPU and can't handle both making all the other request and starting new
the system under test is running out of CPU and has ... the same problem
You will need to monitor them (you are highly advised to do this regardless) as test at 100% runner CPUs are probably not very representable :) and you likely don't want the system you are testing to get to 100% as well.
The status code === 0 means that we couldn't make the request/read the response ... for some reason, usually explained by the error and error_code.
As I commented if you have status code 0 and a body this is most likely a bug ... at least I don't remember there being a case where this won't be true.
The errors you have list mean (most likely):
dial tcp XXX:443: i/o timeout
this is literally we tried to get a tcp connection and it took too long (probably the reason for the big http_req_blocking)
read tcp YYY(local ip):35252->XXX(host ip):443: read: connection reset by peer
the other side closed the connection .. likely because some timeout was reached - for example, if we don't read over 30 seconds the server decides that we won't read anymore and closes it ... and in the case where CPU is 100% there is a good chance some connection won't get time to be read from.
level=warning msg="Request Failed" error="unexpected EOF"
literally, what it says .. the connection was closed when we totally didn't expect, or more accurately the golang net/http stdlib didn't expect. Likely again a timeout just at a point in the life of the request where the other errors aren't returned.
Get https://REQUEST_URL/: context deadline exceeded"
This is because a request took longer then the timeout (by default 60s) and will at some point be changed to a better error message.
Say I want to use FTP in Python using the ftplib. I begin with this:
from ftplib import ftp
ftp = FTP('10.10.10.151')
If the FTP server is not online, however, it will hang right there indefinitely. The only thing that can kick it out is a keyboard interrupt as far as I know. I've tried this:
ftp.connect('10.10.10.151','21', 5)
With the five being a five second timeout. But the problem here is that I do not know of any way to use that line without first assigning ftp something. But if the server is offline, then the "ftp =" line will hang. So what use is ftp.connect()'s timeout function?!?
Does anybody know a workaround or anything? Is there a way to time out the "ftp = FTP(xxx)" command that I haven't found? Thanks.
I'm using Python 2.7 on Linux Mint.
Your call to connect() is redundant since FTP() method documentation states:
When host is given, the method call connect(host) is made.
Also, since Python 2.6, FTP() does have a timeout parameter:
class ftplib.FTP([host[, user[, passwd[, acct[, timeout]]]]])
The optional timeout parameter specifies a timeout in seconds for blocking operations like the connection attempt (if is not specified, the global default timeout setting will be used).
My App is down on Heroku which sucks because we have quite a few users now. The worst part is that I have no idea what the error messages mean...
Does anyone know?
2013-05-15T20:55:58+00:00 app[postgres]: [24612-1] [ORANGE] LOG: checkpoint starting: time
2013-05-15T20:55:58+00:00 app[postgres]: [24613-1] [ORANGE] LOG: checkpoint complete: wrote 0 buffers (0.0%); 0 transaction log file(s) added, 0 removed, 1 recycled; write=0.000 s, sync=0.000 s, total=0.004 s; sync files=0, longest=0.000 s, average=0.000 s
2013-05-15T20:56:38+00:00 app[heroku-postgres]: source=HEROKU_POSTGRESQL_ORANGE measure.current_transaction=28963 measure.db_size=10396472bytes measure.tables=24 measure.active-connections=5 measure.waiting-connections=0 measure.index-cache-hit-rate=0 measure.table-cache-hit-rate=0.99999
This is the only thing on the logs. I've read the Heroku Postgres log statements but for checkpoint complete it says not action needed....
Any ideas? Any help is appreciated.. Thanks
The problem was the custom domain. Only the A (Host) record on GoDaddy was setup, not the CNAME (Alias). Sometimes a configuration change or deploy can put your app on a different set of EC2 IP addresses, which was the case. So even though the app worked for months without a CNAME, as soon as the EC2 IP address changed the custom domain didn't point there anymore.
I changed the A (Host) record and then added a CNAME (Alias). Now everything is back and working.
Hope this helps someone!
I am trying to make a simple UDP packet decoder.
packet_decoder(Packet)->
<<Opts:8,MobIdLength:8,MobId:64,MobIdType:8,MgeType:8,SeqNum:16,Rest/binary>> = Packet,
io:format("Options:~p~n",Opts),
io:format("MobIdLength:~p~n",MobIdLength),
io:format("MobId:~p~n",MobId),
io:format("MobIdType:~p~n",MobIdType),
io:format("MgeType:~p~n",MgeType),
io:format("SeqNum:~p~n",SeqNum).
Packet is passed by a receive loop:
rcv_loop(Socket) ->
inet:setopts(Socket, [{active, once}, binary]),
io:format("rcvr started:~n"),
receive
{udp, Socket, Host, Port, Bin} ->
packet_decoder(Bin),
rcv_loop(Socket)
end.
I keep getting(following error edited 9/7/12 9:30 EST):
** exception error: no match of right hand side value
<<131,8,53,134,150,4,149,0,80,15,1,2,1,2,0,16,80,71,115,
52,80,71,115,53,24,63,227,197,211,...>>
in function udp_server:packet_decoder/1
called as udp_server:packet_decoder(<<131,8,53,134,150,4,149,0,80,15,
1,2,1,2,0,16,80,71,115,52,80,71,
115,53,24,63,227,197,...>>)
in call from udp_server:rcv_loop/1
in call from udp_server:init/0
If I create the same variable in the Erlang shell as a binary, i.e.
Packet = <<131,8,53,134,150,4,149,0,80,15,1,2,1,2,0,16,80,71,115,52,80,71,115,53,24,63,227,197,211,228,89,72,0,0,0,0,0,0,0,16,0,5,5,32,1,4,255,159,15,18,28,0,34,62,2,0,0,0,0,0,0,0,47,67>>.
<<Opts:8,MobIdLength:8,MobId:64,MobIdType:8,MgeType:8,SeqNum:16,Rest/binary>> = Packet.
It works just fine. Is there some subtlety in passing this to a function that I am missing? I have tried what I think is everything(except the right way). I tried setting the type and size. I also just tried
<<Rest/binary>> = Packet.
To no avail. Any help much appreciated.
The error you are getting when you run your code does not match your code. The error you are getting:
** exception error: no match of right hand side value ...
is a badmatch error and comes from an explicit = match where the pattern does not match the value from the RHS. There is no = in the code for rcv_loop/1. This implies that the loop you are running is not this code. So there are some questions to be asked:
When you have recompiled the module containing rcv_loop/1 have you restarted the loop so you run the new code? This is not done automagically.
Are you sure you are loading/running the code you think you are? I know this question sounds stupid but it is very easy, and not uncommon, to work on one version of the code and load another. You need to get the paths right.
The other things about mentioned about your code would not give this error. The calls to io:format/2 are wrong but would result in errors when you make the actual calls to io:format/2. Using the variable Socket as you do is not an error, it just means that you only want to receive UDP packets from just that socket.
EDIT : the first part of my answer was completely wrong so in order to not mislead, I deleted it.
Like spotted Alexey Kachayev io:format takes as second parameter a list, so :
packet_decoder(Packet)->
<<Opts:8,MobIdLength:8,MobId:64,MobIdType:8,MgeType:8,SeqNum:16,Rest/binary>> = Packet,
io:format("Options:~p~n",[Opts]),
io:format("MobIdLength:~p~n",[MobIdLength]),
io:format("MobId:~p~n",[MobId]),
io:format("MobIdType:~p~n",[MobIdType]),
io:format("MgeType:~p~n",[MgeType]),
io:format("SeqNum:~p~n",[SeqNum]).
I figured it out(kinda). I had been working on this in erlide in eclipse which had worked fine for all of the other parts of the. I tried compiling it from the erl shell and it worked fine. There must be some minor difference in the way eclipse is representing the source or the way it invokes the erlang compiler and shell. I will take it up with erlide.org. Thanks for the help!
I have read the RFC1928 several times and still couldn't understand what a compliant SOCKS 5 server is supposed to reply in case of failure. This doubt comes from the fact that the ATYP, BND.ADDR and BND.PORT fields from a SOCKS reply simply don't make sense if, for instance, a request with an invalid command is received. Must the server not send these fields or just send blanks?
I just red putty source code, and found out that, when there is an error in reply (REP != 0) ATYP is IPv4 (1) BND.ADDR and BND.PORT are all NULL bytes.
I guess this behavior helps developpers to parse requests ?
In a failure reply, only the VER and REP fields are meaningful. The other fields may be present but are not used. You don't even need to look at those bytes unless REP is zero.