[Moller_daq] [EXTERNAL] Question: ADC board software - Too many files open core dump

[Robert Michaels]

I haven't encountered this, but I notice that if you Google "Too many open files (src/epoll.cpp:38)" there are several suggestions.   My experience with Googling is that there may be 10 ideas and it ends up that 1 of them works.

yours
Bob


Dr. Robert Michaels

Staff Scientist, Jefferson Lab

http://userweb.jlab.org/~rom

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From: Moller_daq <moller_daq-bounces at jlab.org> on behalf of Michael Gericke <Michael.Gericke at umanitoba.ca>
Sent: Tuesday, January 21, 2025 11:01 AM
To: Zuhal Seyma Demiroglu <zdemirog at jlab.org>; Ciprian Gal <ciprian at jlab.org>; Malte Wilfert <mwilfert at uni-mainz.de>; moller_daq at jlab.org <moller_daq at jlab.org>; moller_analysis at jlab.org <moller_analysis at jlab.org>; bryerton at gmail.com <bryerton at gmail.com>; moller_intdet at jlab.org <moller_intdet at jlab.org>
Subject: [Moller_daq] [EXTERNAL] Question: ADC board software - Too many files open core dump


Hi everyone,

Sorry if you get this multiple times (I am sending to several email lists with significant overlap).

I have an annoying problem. For the PMT testing, I want to run through a given set of tests for each PMT in one sitting (DAQ and analysis program running continuously), which
means starting the ADC DAQ on the computer end once and (currently - ideally) letting it collect upwards of about 1000 5 second long runs at a time for each PMT.  The program
runs fine for about 180 5 second sets and then core dumps with "Too many open files (src/epoll.cpp:38)".

If you have encountered this problem and figured out how to solve it (beyond the band aid suggestions given in online posts), can you please let me know.

Thanks,

Michael


Some more details ...


I am writing both root files and binary files, for the raw data.  The code uses a separate thread to write the root trees, while it keeps getting data from the ADC board continuously.

The thread that writes the root trees and stores them to file is started only once and within it, ROOT files are opened and closed in the same loop. The main process writes
the raw data file and handles the communication with the ADC board. The raw data files are written in a function that both opens and closes each file that is being written.

There are two zmq sockets for communication with the ADC (control and data) and each is opened and closed for each 5 second data chunk that is being received from the ADC
(each single run).

I scoured forums and various information sources, but most of posts I find suggest that once needs to increase the nofile parameter in /proc/sys/fs/file-max or similar.
I have done that, but it doesn't really change anything. It just allows me to take more runs, but doesn't solve the problem.

In principle, I should be able to run this indefinitely (aside from storage space issues).

Of course I could just stop the process and restart periodically (collecting fewer runs at a time), but I want to move through a series of PMT voltages in one run series, with
as little time as possible between changing the HV.

I have encountered this crash every time I start the program and run for extended periods of time (1 hour or more) and it is driving me crazy, because I think the program is written
such that there should not be "many" open files at a time (I think maybe at most 5 at any given time).

The only way around this at the moment is to use a script that restarts the ADC software end after some number of runs before this crash occurs. That's okay, but doesn't resolve
the basic problem.

Somehow I feel like there is either a bug in ZMQ or I am doing something wrong (likely the latter, but some posts I found seem to suggest the possibility of the former).

I don't want to throw a bunch of code at you. For now, I am just wondering if any here has encountered a similar issue and could guess what the problem is.

If anyone wants to take a look (if you have time), the code is located here:

https://github.com/mtgericke/MOLLER-IntElec-PMTGain-Meas<https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_mtgericke_MOLLER-2DIntElec-2DPMTGain-2DMeas&d=DwMDaQ&c=CJqEzB1piLOyyvZjb8YUQw&r=oEOVH2JDjF9X3FqUtWH-nt4bOXao4u2S63djv3IksSA&m=h63pm6kCVRZsJZDv6Qm3IadomS8gZlz-u_jJh_kb06vZdHak21HYvLepNBpUh1Zl&s=LOn7q6CUDdVUcA7WtGX-sjMjpFun4LiiFijDNN2RqTM&e=>

The relevant file is CMData.cxx

The relevant functions are:

void CMData::StartDataCollection()   - file lines 712-733  , 758-781,

void *CMData::GetServerData(void *vargp)  - file line 826

void* CMData::FillRootTreeThread(void *vargp) - file lines 1070, 1293

void* CMData::GetSocket(SockType type)   - file line 458



[cid:part1.lID0TqYH.LVU3AGnA at umanitoba.ca]



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