Log file error

colmfield

Hi,

In my LS logfile I occasionally see the following (once\twice a day with >200 users/day):

20-Sep-10 01:00:10,103 |INFO |LightstreamerLogger.requests     |SERVER POOLED THREAD 10    |Serving request: /lightstreamer/control.js --> LS_session=Sf377070752c55f76T0009244&LS_table=3&LS_win_phase=52&LS_op=add&LS_req_phase=757&LS_mode=MERGE&LS_id=X1%20X2%20X3%20X4%20X5&LS_schema=price%20quantity&LS_data_adapter=PRICES_ADAPTER&LS_snapshot=true&LS_unique=3& from XXX.XXX.XXX.XXX:14287
20-Sep-10 01:00:10,103 |INFO |LightstreamerLogger.requests     |SERVER POOLED THREAD 4     |Controlling session: Sf377070752c55f76T0009244 from XXX.XXX.XXX.XXX:14287
20-Sep-10 01:00:10,478 |INFO |LightstreamerLogger.requests     |SERVER POOLED THREAD 1     |Serving request: /lightstreamer/control.js --> LS_session=Sf377070752c55f76T0009244&LS_table=4&LS_win_phase=52&LS_op=add&LS_req_phase=758&LS_mode=MERGE&LS_id=Control&LS_schema=item%20message&LS_data_adapter=PRICES_ADAPTER&LS_unique=4& from XXX.XXX.XXX.XXX:14287
20-Sep-10 01:00:10,478 |INFO |LightstreamerLogger.requests     |SERVER POOLED THREAD 2     |Controlling session: Sf377070752c55f76T0009244 from XXX.XXX.XXX.XXX:14287
20-Sep-10 01:00:10,588 |INFO |LightstreamerLogger.requests     |SERVER POOLED THREAD 8     |Serving request: /lightstreamer/control.js --> LS_session=S1c0c5f2d12b913daT0007822&LS_table=3&LS_win_phase=25&LS_op=add&LS_req_phase=580&LS_mode=MERGE&[B]LS_id=[/B]&LS_schema=price%20quantity&LS_data_adapter=PRICES_ADAPTER&LS_snapshot=true&LS_unique=3& from XXX.XXX.XXX.XXX:14271
20-Sep-10 01:00:10,588 |INFO |LightstreamerLogger.requests     |SERVER POOLED THREAD 7     |Controlling session: S1c0c5f2d12b913daT0007822 from XXX.XXX.XXX.XXX:14271

You'll notice in the third 'serving request', the LS_id is blank. This causes the following error to be thrown in the MetadataAdapter:

Null or empty item list from getItems for group ''

Is this a client code (Javascript) issue or a bug in LS?

Cheers,
Colm

Mone

it seems a problem with the javascript library, which web client build are you using?

The problem is that the group (the list of items) is empty in the third request, is it possible that you create a table with an empty string as the group?

You may try to enable the remote logging to see if the clients report some errors, see http://www.lightstreamer.com/docs/client_web_jsdoc/Context.html#setRemoteAlertsOnClientError

let us know

colmfield

Hi Mone,

Thanks for your reply.

I can't add the client debug code to the prod servers unfortunately, and have been unable to cause the error in DEV\UAT.

I do play around with the OverwriteTables in the PushPage on the client side so perhaps it's probably related to that.

The way my page is set up, there are a number of tabs displaying live prices, some are LS driven, some are not (using XSL transform and polling to a DB).

When the page is first loaded and displaying an LS tab, a new OverwriteTable is created with a null group, and added to the PushPage:

        // Create the main prices table
        var pushtable = new OverwriteTable(null, schema, 'MERGE');
        pushtable.setSnapshotRequired(true);
        pushtable.onItemUpdate = LSUpdateItem;
        pushtable.onChangingValues = LSFormatValues;
        pushtable.setPushedHtmlEnabled(true);
        pushtable.setDataAdapter('PRICES_ADAPTER');
        LSPushPage.addTable(pushtable, 'pricetable');

If the users switches to a non-LS tab and back again, I run the following (I had to remove and re-add due to job constraints):

        // As the innerHTML is being set each time the tab is changed, a new table ref must be created
        if (LSPushPage) LSPushPage.removeTable('pricetable');
	var pushtable = new OverwriteTable(null, schema, 'MERGE');
        pushtable.setSnapshotRequired(true);
        pushtable.onItemUpdate = LSUpdateItem;
        pushtable.onChangingValues = LSFormatValues;
        pushtable.setPushedHtmlEnabled(true);
	pushtable.setDataAdapter("PRICES_ADAPTER");
	LSPushPage.addTable(pushtable, 'pricetable');

But in all my testing I haven't been able to cause the issue, and I have >200 users all switching tabs relatively regularly and I'm only seeing a handful of errrors, so perhaps this is't the issue at all...

If it helps, the errors always coincide with the "Controlling session" line in the log.

I'm using Vivace 3.6 build 1463.2, Web Client Library version 4.4.1 build 1396.4.

Colm

Mone

Hi,

I was able to reproduce the issue,
It happens If you construct an OverwriteTable keeping null as the first parameter and then, when the addTable is called there are no related-cells on the page. (note that in that case an error message is issued so that if you have the setDebugAlertOnClientError/setRemoteAlertsOnClientError active you'll see it).

Obviously the library should not send the request if it has not the group of the table: this will be fixed in the next version.

Is it possible that switching between your tabs can cause the html tag(s) to be removed?
Maybe you remove it and re-add it later? In this case please be sure that the tags are on the page when addTable is called.

HTH

colmfield

HI,

Thanks for that, makes sense.

@Mone, Wrote:
Is it possible that switching between your tabs can cause the html tag(s) to be removed?
Maybe you remove it and re-add it later? In this case please be sure that the tags are on the page when addTable is called.

It should never happen, but that's not to say it doesn't! I think I have narrowed it down enough to be able to fix it.

Thanks for your help.

Colm