I am running 7 worker processes on a single machine with 4 cores. I may have made a poor choice with this loop while waiting for the result of map_async:
while not result.ready():
time.sleep(10)
for out in result.stdout:
print out
rec_file_list = result.get()
result.stdout keeps growing with all the printed output from the 7 processes running, and it caused the console that initiated the map to hang. The activity monitor on my MacBook Pro shows the 7 processes are still running, and the terminal running the Controller is still active. What are my options here? Is there any way to acquire the result once the processes have completed?
I found an answer:
Remote introspection of ASyncResult objects is possible from another client as long as a 'database backend' has been enabled by the controller with:
ipcontroller --dictb # or --mongodb or --sqlitedb
Then, it is possible to create a new client instance and retrieve the results with:
client.get_result(task_id)
where the task_ids can be retrieved with:
client.hub_history()
Also, a simple way to avoid the buffer overflow I encountered is to periodically print just the last few lines from each engine's stdout history, and to flush the buffer like:
from IPython.display import clear_output
import sys
while not result.ready():
clear_output()
for stdout in result.stdout:
if stdout:
lines = stdout.split('\n')
for line in lines[-4:-1]:
if line:
print line
sys.stdout.flush()
time.sleep(30)
Related
I am using dask to process 10 files which the size of each file is about 142MB. I build a method with delayed tag, following is an example:
#dask.delayed
def process_one_file(input_file_path, save_path):
res = []
for line in open(input_file_path):
res.append(line)
df = pd.DataFrame(line)
df.to_parquet(save_path+os.path.basename(input_file_path))
if __name__ == '__main__':
client = ClusterClient()
input_dir = ""
save_dir = ""
print("start to process")
cvss = [process_one_file(input_dir+filename, save_dir) for filename in os.listdir(input_dir)]
dask.compute(csvs)
However, dask does not always run successfully. After processing all files, the program often hangs.
I used the command line to run the program. The program often huangs after printing start to process. I know the program runs correctly, since I can see all output files after a while.
But the program never stops. If I disabled tls, the program can run successfully.
It was so strange that dask can not stop the program if I enable tls connection. How can I solve it?
I found that if I add to_parquet method, then the program cannot stop, while if I remove the method, it runs successfully.
I have found the problem. I set 10GB for each process. That means I set memory-limit=10GB. I totally set 2 workers and each has 2 processes. Each process has 2 threads.
Thus, each machine will have 4 processes which occupy 40GB. However, my machine only have 32GB. If I lower the memory limit, then the program will run successfully!
We are trying to use Dask to clean up some data as part of an ETL process.
The original file is over 3GB csv .
When we run the code on a subset (1GB) the code runs successfully (with a few user warning regarding our cleaning procedures such as:
ddf[id1] = ddf[id1].str.extract(´(\d+)´)
repeater = re.compile(r´((\d)\2{5,}´)
mask_repeater = ddf[id1].str.contrains(repeater, regex=True)
ddf = ddf[~mask_repeater]
On the 3GB file the process nearly completes (there is only one task left - drop-duplicates-agg) and then restarts from the middle (that is what I can see from the bokeh status website). we also see the warning which is the same as when the script starts to run.
RuntimeWarning: Couldn't detect a suitable IP address for reaching '8.8.8.8', defaulting to '127.0.0.1'...
I´m running on a offline single windows64bit workstation with 24 cores .
Any suggestions?
I wrote a admin script that tails a heroku log and every n seconds, it summarizes averages and notifies me if i cross a certain threshold (yes I know and love new relic -- but I want to do custom stuff).
Here is the entire script.
I have never been a master of IO and threads, I wonder if I am making a silly mistake. I have a couple of daemon threads that have while(true){} which could be the culprit. For example:
# read new lines
f = File.open(file, "r")
f.seek(0, IO::SEEK_END)
while true do
select([f])
line = f.gets
parse_heroku_line(line)
end
I use one daemon to watch for new lines of a log, and the other to periodically summarize.
Does someone see a way to make it less processor-intensive?
This probably runs hot because you never really block while reading from the temporary file. IO::select is a thin layer over POSIX select(2). It looks like you're trying to block until the file is ready for reading, but select(2) considers EOF to be ready ("a file descriptor is also ready on end-of-file"), so you always return right away from select then call gets which returns nil at EOF.
You can get a truer EOF reading and nice blocking behavior by avoiding the thread which writes to the temp file and instead using IO::popen to fork the %x[heroku logs --ps router --tail --app pipewave-cedar] log tailer, connected to a ruby IO object on which you can loop over gets, exiting when gets returns nil (indicating the log tailer finished). gets on the pipe from the tailer will block when there's nothing to read and your script will only run as hot as it takes to do your line parsing and reporting.
EDIT: I'm not set up to actually try your code, but you should be able to replace the log tailer thread and your temp file read loop with this code to get the behavior described above:
IO.popen( %w{ heroku logs --ps router --tail --app my-heroku-app } ) do |logf|
while line = logf.gets
parse_heroku_line(line) if line =~ /^/
end
end
I also notice your reporting thread does not do anything to synchronize access to #total_lines, #total_errors, etc. So, you have some minor race conditions where you can get inconsistent values from the instance vars that parse_heroku_line method updates.
select is about whether a read would block. f is just a plain old file, so you when get to the end reads don't block, they just return nil instantly. As a result select returns instantly rather than waiting for something to be appending to the file as I assume you're expecting. Because of this you're sitting in a tight busy loop, so high cpu is to be expected.
If you are at eof (you could either check f.eof? or whether gets returns nil), then you could either start sleeping (perhaps with some sort of back off) or use something like listen to be notified of filesystem changes
Im using a port to run a pipeline with uncompresses and dd's some data:
Port = open_port({spawn, "bzcat | sudo dd of=/dev/foo},
[stream, use_stdio, exit_status]),
What I would like to do is produce a end-of-file situation on the output which causes the pipeline to complete and eventually exit.
I would like to wait for this completion and also capture the exit_status.
When I just call port_close it looks to me as if the pipeline is just terminated and there is no wait for completion. Also I don't get any exit_status ....
How can I accomplish waiting for exit before my next step (which requires the dd to have completed).
Did some experiments and it looks like at least port_close doesn't kill the process, you just don't find out when its done. Is this correct?
If you just need to wait for spawned by open_port command to complete you need to wait for exit_status message:
1> Port = open_port({spawn, "sleep 7"}, [exit_status]).
#Port<0.497>
2> receive {Port, {exit_status, Code}} -> Code after 10000 -> timeout end.
0
Update (about to say a port just close the output pipe): I think you can't just close the output pipe with the default spawn driver. Default driver doesn't have any control commands and port_close although don't kill spawned command but completely erase all port's state.
Possible solutions:
Write input stream to a file first and then run bzip/dd sequence on that file;
Write your own driver or NIF (Maybe some open source implementations already exist?)
Use some external script and control protocol, for example full (or chunk) length can be transferred before the actual content so the script will know when to close the connection
Several rather ugly workarounds to this problem can be found here: limitations of erlang:open_port() and os:cmd()
Some even use netcat to map the problem to a tcp connection.
I wrote the following two functions, and call the second ("callAndWait") from JavaScript running inside Windows Script Host. My overall intent is to call one command line program from another. That is, I'm running the initial scripting using cscript, and then trying to run something else (Ant) from that script.
function readAllFromAny(oExec)
{
if (!oExec.StdOut.AtEndOfStream)
return oExec.StdOut.ReadLine();
if (!oExec.StdErr.AtEndOfStream)
return "STDERR: " + oExec.StdErr.ReadLine();
return -1;
}
// Execute a command line function....
function callAndWait(execStr) {
var oExec = WshShell.Exec(execStr);
while (oExec.Status == 0)
{
WScript.Sleep(100);
var output;
while ( (output = readAllFromAny(oExec)) != -1) {
WScript.StdOut.WriteLine(output);
}
}
}
Unfortunately, when I run my program, I don't get immediate feedback about what the called program is doing. Instead, the output seems to come in fits and starts, sometimes waiting until the original program has finished, and sometimes it appears to have deadlocked. What I really want to do is have the spawned process actually share the same StdOut as the calling process, but I don't see a way to do that. Just setting oExec.StdOut = WScript.StdOut doesn't work.
Is there an alternate way to spawn processes that will share the StdOut & StdErr of the launching process? I tried using "WshShell.Run(), but that gives me a "permission denied" error. That's problematic, because I don't want to have to tell my clients to change how their Windows environment is configured just to run my program.
What can I do?
You cannot read from StdErr and StdOut in the script engine in this way, as there is no non-blocking IO as Code Master Bob says. If the called process fills up the buffer (about 4KB) on StdErr while you are attempting to read from StdOut, or vice-versa, then you will deadlock/hang. You will starve while waiting for StdOut and it will block waiting for you to read from StdErr.
The practical solution is to redirect StdErr to StdOut like this:
sCommandLine = """c:\Path\To\prog.exe"" Argument1 argument2"
Dim oExec
Set oExec = WshShell.Exec("CMD /S /C "" " & sCommandLine & " 2>&1 """)
In other words, what gets passed to CreateProcess is this:
CMD /S /C " "c:\Path\To\prog.exe" Argument1 argument2 2>&1 "
This invokes CMD.EXE, which interprets the command line. /S /C invokes a special parsing rule so that the first and last quote are stripped off, and the remainder used as-is and executed by CMD.EXE. So CMD.EXE executes this:
"c:\Path\To\prog.exe" Argument1 argument2 2>&1
The incantation 2>&1 redirects prog.exe's StdErr to StdOut. CMD.EXE will propagate the exit code.
You can now succeed by reading from StdOut and ignoring StdErr.
The downside is that the StdErr and StdOut output get mixed together. As long as they are recognisable you can probably work with this.
Another technique which might help in this situation is to redirect the standard error stream of the command to accompany the standard output.
Do this by adding "%comspec% /c" to the front and "2>&1" to the end of the execStr string.
That is, change the command you run from:
zzz
to:
%comspec% /c zzz 2>&1
The "2>&1" is a redirect instruction which causes the StdErr output (file descriptor 2) to be written to the StdOut stream (file descriptor 1).
You need to include the "%comspec% /c" part because it is the command interpreter which understands about the command line redirect. See http://technet.microsoft.com/en-us/library/ee156605.aspx
Using "%comspec%" instead of "cmd" gives portability to a wider range of Windows versions.
If your command contains quoted string arguments, it may be tricky to get them right:
the specification for how cmd handles quotes after "/c" seems to be incomplete.
With this, your script needs only to read the StdOut stream, and will receive both standard output and standard error.
I used this with "net stop wuauserv", which writes to StdOut on success (if the service is running)
and StdErr on failure (if the service is already stopped).
First, your loop is broken in that it always tries to read from oExec.StdOut first. If there is no actual output then it will hang until there is. You wont see any StdErr output until StdOut.atEndOfStream becomes true (probably when the child terminates). Unfortunately, there is no concept of non-blocking I/O in the script engine. That means calling read and having it return immediately if there is no data in the buffer. Thus there is probably no way to get this loop to work as you want. Second, WShell.Run does not provide any properties or methods to access the standard I/O of the child process. It creates the child in a separate window, totally isolated from the parent except for the return code. However, if all you want is to be able to SEE the output from the child then this might be acceptable. You will also be able to interact with the child (input) but only through the new window (see SendKeys).
As for using ReadAll(), this would be even worse since it collects all the input from the stream before returning so you wouldn't see anything at all until the stream was closed. I have no idea why the example places the ReadAll in a loop which builds a string, a single if (!WScript.StdIn.AtEndOfStream) should be sufficient to avoid exceptions.
Another alternative might be to use the process creation methods in WMI. How standard I/O is handled is not clear and there doesn't appear to be any way to allocate specific streams as StdIn/Out/Err. The only hope would be that the child would inherit these from the parent but that's what you want, isn't it? (This comment based upon an idea and a little bit of research but no actual testing.)
Basically, the scripting system is not designed for complicated interprocess communication/synchronisation.
Note: Tests confirming the above were performed on Windows XP Sp2 using Script version 5.6. Reference to current (5.8) manuals suggests no change.
Yes, the Exec function seems to be broken when it comes to terminal output.
I have been using a similar function function ConsumeStd(e) {WScript.StdOut.Write(e.StdOut.ReadAll());WScript.StdErr.Write(e.StdErr.ReadAll());} that I call in a loop similar to yours. Not sure if checking for EOF and reading line by line is better or worse.
You might have hit the deadlock issue described on this Microsoft Support site.
One suggestion is to always read both from stdout and stderr.
You could change readAllFromAny to:
function readAllFromAny(oExec)
{
var output = "";
if (!oExec.StdOut.AtEndOfStream)
output = output + oExec.StdOut.ReadLine();
if (!oExec.StdErr.AtEndOfStream)
output = output + "STDERR: " + oExec.StdErr.ReadLine();
return output ? output : -1;
}