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History plot consuming too much memory

> 
> Are you sure that the delay comes from the browser or actually from mhttpd
> digging through GBytes of history data?
>

I think we will need to address this question "head-on". The history plot
will need to display the following information:

"time to load data from disk: N seconds, time to transfer data to javascript: M 
seconds, time to make the plot: Q seconds".

The second and third items are already available, the first one will need
to be computed in mhttpd and passed to javascript.

K.O.

History plot consuming too much memory

>
> Taking this down a tangent, I have a mild concern that a user could temporarily 
> flood our gigabit network if we do have faster disks to read the history data.
>

By my measurements, right now our javascript code can reach 30-50-70% of Gige ethernet
bandwidth, so, no, we cannot flood the network just by making history plots.

(we cannot reach 100% because javascript code is not multithreaded,
it cycles through "request new data" and "decode javascript, make plot" states,
and the network is idle in this second state).

>
> Have there been any plans or thoughts on limiting the bandwidth users can pull from 
> mhttpd?
>

10gige networking is here (and 5 and 2.5 Gige, too). I would not worry too much
about saturating 1gige network interfaces.

>
> I do not see this as a critical item as I can plan the future network 
> infrastructure at the same time as the next system upgrade (putting critical data 
> taking traffic on a separate physical network).
>

10gige network between all computers, everything on SSD ZFS arrays, except
bulk data on ZFS HDD arrays (only for cost reasons $$$/TB).

K.O.

History panels in custom pages

A new tag has been implemented to display history panels in custom pages, integrated in the 
new custom page design from 2017. The full documentation can be found at 

https://midas.triumf.ca/MidasWiki/index.php/New_Custom_Pages_(2017)#mhistory

Attached is a simple example of such a panel and the result. You have to rename triggerrate.txt to triggerrate.html if you want to use it (can't do it here since otherwise the browser wants to render it which does not work outside of midas).

Stefan

History panels in custom pages

> A new tag has been implemented to display history panels in custom pages, integrated in the 
> new custom page design from 2017. The full documentation can be found at 
> 

As part of consolidating/cleaning the MIDAS Wiki documentation, the "New Custom Pages" was folded into the main "Custom Page".  So to see a
description of Stefan's new functionality please go to 

https://midas.triumf.ca/MidasWiki/index.php/Custom_Page#mhistory

History panels in custom pages

> > A new tag has been implemented to display history panels in custom pages, integrated in the
> > new custom page design from 2017. The full documentation can be found at
> >
>
> As part of consolidating/cleaning the MIDAS Wiki documentation, the "New Custom Pages" was folded into the main "Custom Page". So to see a
> description of Stefan's new functionality please go to
>
> https://midas.triumf.ca/MidasWiki/index.php/Custom_Page#mhistory

Hello!

I am trying to use the new mhistory panels in the WAGASCI slow control custom page, but I cannot get them to work.
All I get is an empty frame. Anyway, in the History tab I can see the history plots correctly.

Here is a minimal example:

<html>
<head>
   <title>Test</title>
   <link rel="stylesheet" href="midas.css">
   <script src="controls.js"></script>
   <script src="midas.js"></script>
   <script src="mhttpd.js"></script>
</head>
<body class="mcss" onload="mhttpd_init('Test');">

<div id="mheader"></div>
<div id="msidenav"></div>

<div id="mmain">
  <div name="mhistory" data-group="Test" data-panel="Test" data-scale="1m" style="width:600px;border:1px solid black;"></div>
</div>
</body>
</html>

Of course, the "Test" group and "Test" panel exist in the ODB and are correctly shown in the History tab. No error is shown in the console of the web browser.
I am using the latest version of MIDAS as of September 12.

Can you confirm that this feature is working in the latest MIDAS? If yes, how can I troubleshoot the problem?

Regards
Giorgio

History panels in custom pages

Indeed there was a bug in some JavaScript code, which I fixed here: https://bitbucket.org/tmidas/midas/commits/d2b1a783240e252820c622001e15c09c5d7798c0

Note that your code will bring you the "old style" history panels (with GIF images). If you want the new style (interactive canvas panels), you need the following:

1) Add

<script src="mhistory.js"></Script>

to the top of your custom page

2) Add "mhistory_init();" to the "onload" function of your page, like

<body class="mcss" onloas="mhttpd_init('Example');mhistory_init();">

3) Change the class of the panel from "mhistory" to "mjhistory", like

<div class="mjshistory" data-group=...>

Best regards,
Stefan

History panels in custom pages

Dear Stefan,
thank you very much for the prompt reply. Your suggestions worked wonderfully. Now I can display all the plots that I want where I want.
The new JavaScript history plots are really a huge improvement over the old ones.
Thank you again
Giorgio

Stefan Ritt wrote:

History formula not correctly managed

OS: OSX 10.14.6 Mojave
MIDAS: Downloaded from repo on April 2021.

I have a slow control frontend doing the command/readout of a MPOD HV/LV. Since I am reading out the current that are in nA (after updating snmp), I wanted to multiply the number by 1e9.

I noticed the new "Formula" field (introduced in 2019 it seems) instead of the "Factor/Offset" I was used to. None of my entries seems to be accepted (after hitting save, when coming back thee field is empty).

Looking in ODB in "/History/Display/MPOD/HV (Current)/", the field "Formula" is a string of size 32 (even if I have multiple plots in that display). I noticed that the fields "Factor" and "Offset" are still existing and they are arrays with the correct size. However, changing the values does not seem to do anything.

Deleting "Formula" by hand and creating a new field as an array of string (of correct length) seems to do the trick: the formula is displayed in the History display config, and correctly used.

History formula not correctly managed

> OS: OSX 10.14.6 Mojave
> MIDAS: Downloaded from repo on April 2021.
> 
> I have a slow control frontend doing the command/readout of a MPOD HV/LV. Since I am reading out the current that are in nA (after updating snmp), I wanted to multiply the number by 1e9.
> 
> I noticed the new "Formula" field (introduced in 2019 it seems) instead of the "Factor/Offset" I was used to. None of my entries seems to be accepted (after hitting save, when coming back thee field is empty).
> 
> Looking in ODB in "/History/Display/MPOD/HV (Current)/", the field "Formula" is a string of size 32 (even if I have multiple plots in that display). I noticed that the fields "Factor" and "Offset" are still existing and they are arrays with the correct size. However, changing the values does not seem to do anything.
> 
> Deleting "Formula" by hand and creating a new field as an array of string (of correct length) seems to do the trick: the formula is displayed in the History display config, and correctly used.

I see this, too. Problem is that the history plot code must be compatible with both
the old scheme (factor/offset) and the new scheme (formula). But something goes wrong somewhere.

https://bitbucket.org/tmidas/midas/issues/307/history-plot-config-incorrect-in-odb

Why?

- new code cannot to "3 year" plots, old code has no problem with it
- old experiments (alpha1, etc) have only the old-style history plot definitions,
and both old and new plotting code should be able to show them (there is nobody
to convert this old stuff to the "new way", but we still desire to be able to look at it!)

K.O.

History data size mismatch

Logging a list of variables to the history via links in the history ODB subtree,
we get messages as follows at every run start:

19:43:24.009 2019/10/06 [Logger,ERROR] [history_schema.cxx:2676:hs_write_event,ERROR] Event 'System' data size mismatch: expected 412 bytes, got 416 bytes

19:43:24.008 2019/10/06 [Logger,ERROR] [history_schema.cxx:2676:hs_write_event,ERROR] Event 'System' data size mismatch: expected 412 bytes, got 416 bytes

19:43:23.850 2019/10/06 [Logger,ERROR] [history_schema.cxx:455:hs_write_event,ERROR] Event 'System' data size mismatch count: 25, expected 412 bytes, hs_write_event() called with as much as 416 bytes

19:43:23.850 2019/10/06 [Logger,ERROR] [history_schema.cxx:455:hs_write_event,ERROR] Event 'System' data size mismatch count: 25, expected 412 bytes, hs_write_event() called with as much as 416 bytes

The history calculates the size of a record from the size of the individual variables, (history_schema.cxx, L2666 ff), whereas the ODB delivers the data aligned/padded to the size of the largest value in the record.
In our history, a long list of doubles (64 Bit) fas followed by three floats (32 bit), leading to a padded response from the ODB, 4 byte longer than the history expects.
Quick fix: Add another 32 bit dummy variable to the history. Gets rid of the error messages...
Should probably be fixed at a deeper level...

History data size mismatch

I wonder why do you this via ODB links. The "standard" way of writing to the history should be to create events for an equipment and flag this equipment as being written to the
history. All variables under /Equipment/<name>/Variables then automatically go into the history and you don't have to worry about ODB links. Only variables not fitting the
equipment/variables scheme should be dealt with via ODB links, like variables under equipment/statistics or parameters in another ODB tree. In a typical midas experiment, only
very few variables typically go into the 'System' event. This is however probably not a solution to your problem. If you have a similar structure (doubles plus an odd number of floats)
under 'variables', you might get the same error. I'n in contact with KO to fix this problem at the root level.

Stefan

> Logging a list of variables to the history via links in the history ODB subtree,
> we get messages as follows at every run start:
> 
> 19:43:24.009 2019/10/06 [Logger,ERROR] [history_schema.cxx:2676:hs_write_event,ERROR] Event 'System' data size mismatch: expected 412 bytes, got 416 bytes
> 
> 19:43:24.008 2019/10/06 [Logger,ERROR] [history_schema.cxx:2676:hs_write_event,ERROR] Event 'System' data size mismatch: expected 412 bytes, got 416 bytes
> 
> 19:43:23.850 2019/10/06 [Logger,ERROR] [history_schema.cxx:455:hs_write_event,ERROR] Event 'System' data size mismatch count: 25, expected 412 bytes, hs_write_event() called with as much as 416 bytes
> 
> 19:43:23.850 2019/10/06 [Logger,ERROR] [history_schema.cxx:455:hs_write_event,ERROR] Event 'System' data size mismatch count: 25, expected 412 bytes, hs_write_event() called with as much as 416 bytes
> 
> The history calculates the size of a record from the size of the individual variables, (history_schema.cxx, L2666 ff), whereas the ODB delivers the data aligned/padded to the size of the largest value in the record.
> In our history, a long list of doubles (64 Bit) fas followed by three floats (32 bit), leading to a padded response from the ODB, 4 byte longer than the history expects.
> Quick fix: Add another 32 bit dummy variable to the history. Gets rid of the error messages...
> Should probably be fixed at a deeper level...

History data size mismatch

>
> In our history, a long list of doubles (64 Bit) fas followed by three floats (32 bit)
>

Padding trouble, mixing "double" and "float" trouble. Ouch.

Best wisdom I received on this: never use "float", always use "double".

I was burned by "float" with following code, which produced the same result from
analyzing 100 files as from analyzing 1000 files. (why did we take data for 10 weeks
instead of 1 week?). Hint: "float" overflows way too quickly, after overflow sum+=1 does not change
the value of "sum". The actual code used ROOT TH1F. Lesson: always use TH1D.

float sum = 0; // should always be "double" !!!
foreach data_file {
    foreach data from current data file {
        sum += data;
    }   
}
print sum;

K.O.

History data size mismatch

>I wonder why do you this via ODB links. The "standard" way of writing to the history should be to create events for an equipment and flag this equipment as being written to the
>history. All variables under /Equipment/<name>/Variables then automatically go into the history and you don't have to worry about ODB links. Only variables not fitting the
>equipment/variables scheme should be dealt with via ODB links, like variables under equipment/statistics or parameters in another ODB tree. In a typical midas experiment, only
>very few variables typically go into the 'System' event. This is however probably not a solution to your problem. If you have a similar structure (doubles plus an odd number of floats)
>under 'variables', you might get the same error.

>
> In our history, a long list of doubles (64 Bit) fas followed by three floats (32 bit)
>

We do this in the MuX DAQ and mix things that come directly from MIDAS (the MIDAS trigger rate) and things from the
analyzer (rates in the self-triggering detectors) and some temperatures from yet somewhere else. Yes, we could have
kept that apart, yes, in this case a double would also work (and not break things), but a bug is a bug...
I could think of senisble use cases where doubles and ints are mixed and I also know quite a few areas where it makes
sense to use floats...

Nik

History data size mismatch

> Yes, we could have
> kept that apart, yes, in this case a double would also work (and not break things), but a bug is a bug...
> I could think of senisble use cases where doubles and ints are mixed and I also know quite a few areas where it makes
> sense to use floats...

I agree with Nik that we should fix this on the midas level. Since it happens in history_schema.cxx which was written by KO, maybe he can have a look.

Stefan

History SQL database poll: MySQL, PgSQL, ODBC?

I would like to hear from potential users on which SQL database would be
preferable for storage of MIDAS history data.

My current preference is to use the ODBC interface, leaving the choice of
database engine to the user. While ODBC is not pretty, it appears to be adequate
for the job, permits "funny" databases (i.e. flat files) and I already have
prototype implementations for reading (mhttpd) and writing (mhdump/mlogger)
history data using ODBC.

In practice, MySQL and PgSQL are the main two viable choices for using with the
MIDAS history system. We tested both (no change in code - just tell ODBC which
driver to use) and both provide comparable performance and disk space use. We
were glad to see that the disk space use by both SQL databases is very
efficient, only slightly worse than uncompressed MIDAS history files.

At TRIUMF, for T2K/ND280, we now decided to use MySQL - it provides a better
match to MIDAS data types (has 1-byte and 2-byte integers, etc) and appears to
have working database replication (required for our use).

With mlogger already including support for MySQL, and MySQL being a better match
for MIDAS data, this gives them a slight edge and I think it would be reasonable
choice to only implement support for MySQL.

So I see 3 alternatives:

1) use ODBC (my preference)
2) use MySQL exclusively
3) implement a "midas odbc layer" supporting either MySQL or PgSQL.

Before jumping either way, I would like to hear from you folks.

K.O.

Hide start and stop buttons

The wiki documents an odb variable to enable the hiding of the Start and Stop buttons on the mhttpd status page
https://daq00.triumf.ca/MidasWiki/index.php//Experiment_ODB_tree#Start-Stop_Buttons

However mhttpd states this option is obsolete. See commit:
https://bitbucket.org/tmidas/midas/commits/2366eefc6a216dc45154bc4594e329420500dcf7

I note that that commit also made mhttpd report that the "Pause-Resume Buttons" variable is also obsolete, however that code seems to have since been removed.

Is there now some other mechanism to hide the start and stop buttons?
Note that this is for a pure slow control system that does not take runs.

Hide start and stop buttons

> Is there now some other mechanism to hide the start and stop buttons?
> Note that this is for a pure slow control system that does not take runs.

Just wanted to add that I realize that this can be done by copying
status.html and/or midas.css to the experiment directory and then modifying
them/it, but wonder if the is some other preferred way.

Hide start and stop buttons

Indeed the ODB settings are obsolete. Now that the status page is fully dynamic 
(JavaScript), it's much more powerful to modify the status.html page directly. You 
can not only hide the buttons, but also remove the run numbers, the running time, 
and so on. This is much more flexible than steering things through the ODB.

If there is a general need for that, I can draft a "non-run" based status page, but 
it's a bit hard to make a one-fits-all. Like some might even remove the logging 
channels and the clients, but add certain things like if their slow control front-
end is running etc.

Best,
Stefan

Hide start and stop buttons

Hi Stefan,

> Indeed the ODB settings are obsolete.

I just applied for an account for the wiki.
I'll try add a note regarding this change.

> Now that the status page is fully dynamic 
> (JavaScript), it's much more powerful to modify the status.html page directly. You 
> can not only hide the buttons, but also remove the run numbers, the running time, 
> and so on. This is much more flexible than steering things through the ODB.

Very true. Currently I copied the resources/midas.css into the experiment directory and appended:

#runNumberCell { display: none;}
#runStatusStartTime { display: none;}
#runStatusStopTime { display: none;}
#runStatusSequencer { display: none;}
#logChannel { display: none;}

See screenshot attached. :-)

But if feels a little clunky to copy the whole file just to add five lines.
It might be more elegant if status.html looked for a user css file in addition
to the default ones.

> If there is a general need for that, I can draft a "non-run" based status page, but 
> it's a bit hard to make a one-fits-all. Like some might even remove the logging 
> channels and the clients, but add certain things like if their slow control front-
> end is running etc.

The logging channels are easily removed with the css (see attachment), but it might be
nice if the string "Run Status" table title was also configurable by css. For this
slow control system I'd probably change it to something like "GSC Status". Again
this is a minor thing, I could trivially do this by copying the resources/status.html
to the experiment directory and editing it.

Lots of fun new stuff migrating from circa 2012 midas to midas-2022-05-c :-)

Cheers,

Nick.

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