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Hello,
> Tomasz
> Regarding my problem with Amibroker consuming 100% CPU for certain
> stocks, I can add the following information:
> 1. I enabled "Display Plugin Activity" in Preferences and set the
> Realtime chart refresh interval to the maximum of "30" seconds.
> 2. Database setting is set for loading 5000 bars and local storage is
> disabled (for now).
> 3. For tickers that appear to work OK, the status bar
> reports "Processing data through plugin" result "8460 data bars
> retrieved during 2.351 sec". The number of bars and time taken varies
> for each ticker and at each realtime refresh interval. I am not sure
> why the quantity of data bars varies from that configured in the
> database.
Maybe you have entered 50000 bars instead of 5000 (by mistake). Please check.
As for the time it takes to get the data: the plugin is limited by the speed
of Marketcast Database API, in order to improve perfomance please
ENABLE local database storage (in File->Database Settings) as enabling it allows to
get all the quotes only once and then getting only new updates instead
of retrieving all history over and over again.
> 4. For a ticker where there seems to be a data retrieval problem
> (i.e. suspect ticker)the chart retrieval takes about 20 seconds, and
> the status bar reports 18-21 seconds. But Amibroker appears to
> initial a second retrieval immediately after the first.
Then it is the problem of Database API. Please report the ticker symbol
to MarketCast and please tell them that Database API takes 20 seconds
to retrieve the data. Otherwise provide this information (the symbol
and time) to support[at]amibroker.com and I will forward
it with appropriate comment to MarketCast staff.
> 5. After the initial "double" retrieval as described in item 4. for
> suspect tickers data retrieval is carried out once only per realtime
> scan interval. For healthy tickers the data retrieval appears to
> occur only once per realtime interval included the first time.
Yes that's true but only as long as data can be cached in in-memory (RAM) cache.
If you want to cache more data locally (more than just in RAM memory)
please ENABLE local database storage.
This will definitely improve performance.
> 6. My 100% CPU usage and loss of control of Amibroker was a result of
> the plugin taking longer than the realtime refresh interval to
> retrieve data. Thus, almost no "free" time was allocated to servicing
> the user. It is possible to "queue" so to speek a single mouse click
> or key press to exit the application which would eventually be
> serviced.
Yes the Database API is somewhat slow, however after initial (slow)
retrieval of data and local database enabled you should be able to
get subsequent updates quite fast, since not all history but only missing
part is retrieved.
>
> So, there is clearly a problem somewhere in the data retrieval
> process and I will see how well marketcast can help me in this
> regard. There also appears to be a double retrieval which I am
> guessing is a result of an error after the first initial query. I
> hope this makes sense.
Your assumptions are correct.
MarketCast plugin uses MarketCastGetTrade Database API function to
retrieve historical intraday data and spends 90% of time inside
MarketCastGetTrade function.
Best regards,
Tomasz Janeczko
amibroker.com
----- Original Message -----
From: "Chris" <shawky2004@xxxxxxxxxxxxxx>
To: <amibroker@xxxxxxxxxxxxxxx>
Sent: Saturday, September 25, 2004 10:25 AM
Subject: [amibroker] Re: Problem with MarketCast data feed into Amibroker
>
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