Sometimes (perhaps once a day, on average) one (any one) of my charts that I have open in the JForex platform will stop plotting. The chart just "freezes". That particular chart no longer seems to receive ticks. Whenever this happens, I usually only notice after a number of hours have passed.

When this problem occurs, some of the characteristics I have noted are:
1. The bid/ask prices in the side panel continue updating, and are no longer consistent with the last price where the chart froze.
2. The clock in the top right corner loops around the same 10 second loop continuously.
3. The problem disappears (i.e. the frozen chart continues plotting) after a new chart (of any instrument) is opened.
4. The problem disappears (i.e. the frozen chart continues plotting) after the platform gets subscribed to any new instrument.
5. The problem disappears (i.e. the frozen chart continues plotting) after the platform gets unsubscribed from another instrument.

Here is a dump of the Java console after this had happened and I pursued action 4 above on the 8th at 10:59.

Java Web Start 10.10.2.18
Using JRE version 1.7.0_10-b18 Java HotSpot(TM) Client VM
User home directory = C:\Users\isak
----------------------------------------------------
c:   clear console window
f:   finalize objects on finalization queue
g:   garbage collect
h:   display this help message
m:   print memory usage
o:   trigger logging
p:   reload proxy configuration
q:   hide console
r:   reload policy configuration
s:   dump system and deployment properties
t:   dump thread list
v:   dump thread stack
0-5: set trace level to <n>
----------------------------------------------------
Could not launch from cache. Will try online mode. [Some of required resources are not cached.]
   Match: beginTraversal
Match: digest selected JREDesc: JREDesc[version 1.6+, heap=33554432-536870912, args=null, href=null, sel=false, null, null], JREInfo: JREInfo for index 0:
    platform is: 1.7
    product is: 1.7.0_10
    location is: https://java.sun.com/products/autodl/j2se
    path is: C:\Program Files\Java\jre7\bin\javaw.exe
    args is: null
    native platform is: Windows, x86 [ x86, 32bit ]
    JavaFX runtime is: JavaFX 2.2.4 found at C:\Program Files\Java\jre7\
    enabled is: true
    registered is: true
    system is: true

   Match: selecting maxHeap: 536870912
   Match: selecting InitHeap: 33554432
   Match: digesting vmargs: null
   Match: digested vmargs: [JVMParameters: isSecure: true, args: ]
   Match: JVM args after accumulation: [JVMParameters: isSecure: true, args: ]
   Match: digest LaunchDesc: https://www.dukascopy.com/client/demo/jclient/jforex.jnlp
   Match: digest properties: [-Djnlp.client.version=2.22.2, -Djnlp.platform.mode=jforex, -Djnlp.client.mode=DEMO, -Djnlp.login.url=https://www1.dukascopy.com/authorization/demo,https://www2.dukascopy.com/authorization/demo,https://www6.dukascopy.com/authorization/demo, -Dsun.java2d.d3d=false]
   Match: JVM args: [JVMParameters: isSecure: true, args: -Djnlp.client.version=2.22.2 -Djnlp.platform.mode=jforex -Djnlp.client.mode=DEMO -Djnlp.login.url=https://www1.dukascopy.com/authorization/demo,https://www2.dukascopy.com/authorization/demo,https://www6.dukascopy.com/authorization/demo -Dsun.java2d.d3d=false]
   Match: endTraversal ..
   Match: JVM args final: -Xmx512m -Xms32m -Djnlp.client.version=2.22.2 -Djnlp.platform.mode=jforex -Djnlp.client.mode=DEMO -Djnlp.login.url=https://www1.dukascopy.com/authorization/demo,https://www2.dukascopy.com/authorization/demo,https://www6.dukascopy.com/authorization/demo -Dsun.java2d.d3d=false
   Match: Running JREInfo Version    match: 1.7.0.10 == 1.7.0.10
    Match: Running JVM args match: have:<-Xms32m -Djnlp.client.version=2.22.2 -Djnlp.platform.mode=jforex -Djnlp.client.mode=DEMO -Djnlp.login.url=https://www1.dukascopy.com/authorization/demo,https://www2.dukascopy.com/authorization/demo,https://www6.dukascopy.com/authorization/demo -Dsun.java2d.d3d=false -Djnlp.client.username=DEMO2gZsug -Djnlp.client.password=gZsug -Xmx512m -Xms32m -Dsun.java2d.d3d=false>  satisfy want:<-Xmx512m -Xms32m -Djnlp.client.version=2.22.2 -Djnlp.platform.mode=jforex -Djnlp.client.mode=DEMO -Djnlp.login.url=https://www1.dukascopy.com/authorization/demo,https://www2.dukascopy.com/authorization/demo,https://www6.dukascopy.com/authorization/demo -Dsun.java2d.d3d=false>
07.01.2013 12:54:19.994     INFO                         util.u ] Starting Resource Preloader Hardlinker.
07.01.2013 12:54:20.025     INFO                         util.u ] Final Hard Refs: size: 42
07.01.2013 12:54:58.518  WARNING      connect.JForexTaskManager ] Got tick for instrument [GBP/USD] that was not processed by FeedDataProvider... Instrument subscription status [false] MarketState [{"tlb":"140.33","apa":"1.6058","a":"1.60567,1.88,0.0","t":"1357556015440","apb":"1.60541","b":"1.60555,1.5,0.0","pip":"0.0001","i":"GBP/USD","type":"marketState","tla":"160.14"}]
07.01.2013 12:55:03.113  WARNING      connect.JForexTaskManager ] Got tick for instrument [GBP/USD] that was not processed by FeedDataProvider... Instrument subscription status [false] MarketState [{"tlb":"150.98","apa":"1.60582","a":"1.60567,1.13,0.0","t":"1357556020247","apb":"1.60541","b":"1.60557,2.25,0.0","pip":"0.0001","i":"GBP/USD","type":"marketState","tla":"138.03"}]
07.01.2013 12:55:03.832  WARNING      connect.JForexTaskManager ] Got tick for instrument [GBP/USD] that was not processed by FeedDataProvider... Instrument subscription status [false] MarketState [{"tlb":"131.67","apa":"1.60588","a":"1.60575,4.35,0.0","t":"1357556020527","apb":"1.60547","b":"1.60561,1.5,0.0","pip":"0.0001","i":"GBP/USD","type":"marketState","tla":"157.98"}]
07.01.2013 12:55:04.327  WARNING      connect.JForexTaskManager ] Got tick for instrument [GBP/USD] that was not processed by FeedDataProvider... Instrument subscription status [false] MarketState [{"tlb":"151.92","apa":"1.60591","a":"1.60576,2.18,0.0","t":"1357556021099","apb":"1.60548","b":"1.60562,3.15,0.0","pip":"0.0001","i":"GBP/USD","type":"marketState","tla":"150.96"}]
07.01.2013 12:55:04.806  WARNING      connect.JForexTaskManager ] Got tick for instrument [GBP/USD] that was not processed by FeedDataProvider... Instrument subscription status [false] MarketState [{"tlb":"162.15","apa":"1.60587","a":"1.60571,2.48,0.0","t":"1357556021657","apb":"1.60543","b":"1.60562,1.5,0.0","pip":"0.0001","i":"GBP/USD","type":"marketState","tla":"145.89"}]
07.01.2013 12:55:05.300  WARNING      connect.JForexTaskManager ] Got tick for instrument [GBP/USD] that was not processed by FeedDataProvider... Instrument subscription status [false] MarketState [{"tlb":"163.83","apa":"1.60586","a":"1.60571,1.73,0.0","t":"1357556022197","apb":"1.60543","b":"1.60560,1.05,0.0","pip":"0.0001","i":"GBP/USD","type":"marketState","tla":"146.91"}]
07.01.2013 12:55:06.496  WARNING      connect.JForexTaskManager ] Got tick for instrument [GBP/USD] that was not processed by FeedDataProvider... Instrument subscription status [false] MarketState [{"tlb":"138.04","apa":"1.60586","a":"1.60571,2.55,0.0","t":"1357556023599","apb":"1.60543","b":"1.60557,1.65,0.0","pip":"0.0001","i":"GBP/USD","type":"marketState","tla":"132.51"}]
07.01.2013 12:55:07.050  WARNING      connect.JForexTaskManager ] Got tick for instrument [GBP/USD] that was not processed by FeedDataProvider... Instrument subscription status [false] MarketState [{"tlb":"144.72","apa":"1.60584","a":"1.60569,2.25,0.0","t":"1357556024153","apb":"1.60541","b":"1.60556,1.65,0.0","pip":"0.0001","i":"GBP/USD","type":"marketState","tla":"149.57"}]
07.01.2013 12:55:07.722  WARNING      connect.JForexTaskManager ] Got tick for instrument [GBP/USD] that was not processed by FeedDataProvider... Instrument subscription status [false] MarketState [{"tlb":"156.22","apa":"1.60582","a":"1.60569,2.48,0.0","t":"1357556024820","apb":"1.60541","b":"1.60555,1.88,0.0","pip":"0.0001","i":"GBP/USD","type":"marketState","tla":"159.02"}]
07.01.2013 12:55:08.380  WARNING      connect.JForexTaskManager ] Got tick for instrument [GBP/USD] that was not processed by FeedDataProvider... Instrument subscription status [false] MarketState [{"tlb":"153.53","apa":"1.6058","a":"1.60567,1.13,0.0","t":"1357556025480","apb":"1.60541","b":"1.60555,1.5,0.0","pip":"0.0001","i":"GBP/USD","type":"marketState","tla":"148.65"}]
07.01.2013 12:55:09.872  WARNING                     connect.cm ] White Label Image is not received
08.01.2013 10:59:35.681  WARNING      connect.JForexTaskManager ] Got tick for instrument [EUR/JPY] that was not processed by FeedDataProvider... Instrument subscription status [false] MarketState [{"tlb":"114.29","apa":"114.782","a":"114.765,1.13,0.0,114.767,1.73,0.0,114.768,1.5,0.0,114.769,9.38,0.0,114.771,3.75,0.0,114.774,5.63,0.0,114.775,8.63,0.0,114.776,4.7,0.0,114.777,6.05,0.0,114.780,21.33,0.0","t":"1357635544139","apb":"114.739","b":"114.754,1.5,0.0,114.752,2.48,0.0,114.751,1.5,0.0,114.749,4.13,0.0,114.748,9.38,0.0,114.747,5.25,0.0,114.745,9.95,0.0,114.744,11.25,0.0,114.743,10.95,0.0,114.741,27.03,0.0","pip":"0.01","i":"EUR/JPY","type":"marketState","tla":"98.63"}]

I have been observing this bug for years, intermittently.

Further testing resulted in EDIT1 above.

After further observation, I have edited the original post substantially, clarifying and adding some more details.

I don't know whether this is related or not, but the problem described in the original post happened again and I found this in the Java console:

30.01.2013 15:23:18.000     INFO                         util.u ] Starting Resource Preloader Hardlinker.
30.01.2013 15:23:18.032     INFO                         util.u ] Final Hard Refs: size: 42
30.01.2013 15:24:07.738  WARNING                   datacache.cj ] Deserialization error, unknown header [???*?]
java.io.StreamCorruptedException: Deserialization error, unknown header [???*?]
   at com.dukascopy.charts.data.datacache.cq.a(Unknown Source)
   at com.dukascopy.charts.data.datacache.cj.a(Unknown Source)
   at com.dukascopy.charts.data.datacache.CurvesDataLoader.a(Unknown Source)
   at com.dukascopy.charts.data.datacache.CurvesDataLoader.a(Unknown Source)
   at com.dukascopy.charts.data.datacache.cd.run(Unknown Source)
   at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
   at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
   at java.util.concurrent.FutureTask.run(Unknown Source)
   at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
   at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
   at java.lang.Thread.run(Unknown Source)
30.01.2013 15:24:08.360  WARNING                   datacache.cj ] Deserialization error, unknown header [?y?:?]
java.io.StreamCorruptedException: Deserialization error, unknown header [?y?:?]
   at com.dukascopy.charts.data.datacache.cq.a(Unknown Source)
   at com.dukascopy.charts.data.datacache.cj.a(Unknown Source)
   at com.dukascopy.charts.data.datacache.CurvesDataLoader.a(Unknown Source)
   at com.dukascopy.charts.data.datacache.CurvesDataLoader.a(Unknown Source)
   at com.dukascopy.charts.data.datacache.cd.run(Unknown Source)
   at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
   at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
   at java.util.concurrent.FutureTask.run(Unknown Source)
   at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
   at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
   at java.lang.Thread.run(Unknown Source)
30.01.2013 15:24:49.847  WARNING      connect.JForexTaskManager ] Got tick for instrument [EUR/USD] that was not processed by FeedDataProvider... Instrument subscription status [false] MarketState [{"tlb":"131.83","apa":"1.35391","a":"1.35380,1.13,0.25,1.35382,1.5,2.0,1.35383,3.94,2.0,1.35384,5.63,2.0,1.35385,9.38,2.0,1.35386,11.45,3.03,1.35388,8.45,3.03,1.35389,38.93,3.03,1.35390,5.63,3.03,1.35393,37.45,3.03","t":"1359552292897","apb":"1.35365","b":"1.35375,1.5,4.2,1.35374,2.25,4.2,1.35373,2.25,4.2,1.35372,8.63,4.2,1.35371,19.13,4.2,1.35369,8.45,4.2,1.35368,7.33,4.2,1.35367,3.75,4.2,1.35366,29.13,4.2,1.35362,34.83,4.2","pip":"0.0001","i":"EUR/USD","type":"marketState","tla":"139.42"}]
30.01.2013 15:24:50.420  WARNING      connect.JForexTaskManager ] Got tick for instrument [EUR/USD] that was not processed by FeedDataProvider... Instrument subscription status [false] MarketState [{"tlb":"166.92","apa":"1.35391","a":"1.35380,1.13,2.67,1.35382,2.48,2.67,1.35383,3.75,2.67,1.35384,9.0,2.67,1.35385,15.0,2.67,1.35386,7.5,2.67,1.35387,6.95,2.67,1.35388,17.13,2.67,1.35389,23.68,2.67,1.35393,39.63,2.67","t":"1359552293198","apb":"1.35362","b":"1.35375,2.63,4.0,1.35374,2.25,4.0,1.35373,1.5,4.0,1.35372,7.7,4.0,1.35371,16.88,4.0,1.35370,13.13,4.0,1.35368,9.2,4.0,1.35367,4.7,4.0,1.35366,23.5,4.0,1.35362,54.23,4.0","pip":"0.0001","i":"EUR/USD","type":"marketState","tla":"140.19"}]
30.01.2013 15:24:50.967  WARNING      connect.JForexTaskManager ] Got tick for instrument [EUR/USD] that was not processed by FeedDataProvider... Instrument subscription status [false] MarketState [{"tlb":"159.5","apa":"1.35392","a":"1.35382,1.13,2.0,1.35383,4.5,2.0,1.35385,1.5,2.0,1.35386,5.83,2.37,1.35387,11.25,2.37,1.35388,16.43,2.37,1.35389,37.05,2.37,1.35390,5.63,2.37,1.35393,4.13,2.37,1.35394,45.2,2.37","t":"1359552293718","apb":"1.35363","b":"1.35376,1.65,1.0,1.35375,1.73,1.0,1.35374,3.0,1.0,1.35373,5.63,1.0,1.35372,7.7,2.34,1.35370,9.38,6.2,1.35369,5.63,6.2,1.35368,7.33,6.2,1.35367,7.5,6.2,1.35366,72.78,6.2","pip":"0.0001","i":"EUR/USD","type":"marketState","tla":"141.92"}]
30.01.2013 15:24:50.967  WARNING      connect.JForexTaskManager ] Got tick for instrument [EUR/USD] that was not processed by FeedDataProvider... Instrument subscription status [false] MarketState [{"tlb":"159.19","apa":"1.35393","a":"1.35381,1.13,1.0,1.35383,3.75,2.0,1.35385,4.5,2.0,1.35386,3.95,2.37,1.35387,7.5,2.37,1.35388,16.43,2.37,1.35389,20.88,2.37,1.35390,21.8,2.37,1.35393,4.13,2.37,1.35395,45.2,2.37","t":"1359552293877","apb":"1.35363","b":"1.35375,3.38,1.0,1.35374,3.0,1.0,1.35372,3.83,2.34,1.35371,4.7,2.34,1.35370,8.45,6.2,1.35369,5.63,6.2,1.35368,7.33,6.2,1.35367,7.5,6.2,1.35366,22.88,6.2,1.35365,58.95,6.2","pip":"0.0001","i":"EUR/USD","type":"marketState","tla":"138.54"}]
30.01.2013 15:24:54.452  WARNING      connect.JForexTaskManager ] Got tick for instrument [EUR/USD] that was not processed by FeedDataProvider... Instrument subscription status [false] MarketState [{"tlb":"138.48","apa":"1.35393","a":"1.35380,1.88,0.25,1.35382,1.5,1.0,1.35383,1.5,1.0,1.35384,11.73,1.0,1.35385,16.88,1.0,1.35386,13.33,2.37,1.35387,6.58,2.37,1.35388,9.63,2.37,1.35389,7.5,2.37,1.35390,47.5,2.37","t":"1359552297467","apb":"1.35362","b":"1.35375,1.5,2.0,1.35374,3.0,2.2,1.35372,2.85,2.34,1.35371,11.83,2.34,1.35370,10.7,2.34,1.35369,2.83,2.34,1.35368,8.25,2.34,1.35367,10.33,2.34,1.35366,17.13,2.34,1.35365,37.48,2.34","pip":"0.0001","i":"EUR/USD","type":"marketState","tla":"156.34"}]
30.01.2013 15:25:06.170  WARNING                     connect.cj ] White Label Image is not received

You might wanna be sure you have enough Java heap. Instead of using default heap sizes,
which are set with Dukas jnlp link, you might consider "filtering" that to specify larger
heap sizes ??
Just an idea. Several posters in here have shown how heap specifications can be
influenced, and I've posted a .vbs file which downloads the jnlp, filters it, and then
executes with a range of advanced settings.

You could be running Strategy modules with "memory leaks". Yeah, I know
Java doesn't have memory leaks, but if the software is hanging onto objects,
then heap usage will be exhausted, since GC can't happen. So maybe you're
just exhausting heap somehow.

Use the Tools Preferences Advanced to show your Java heap on the lower
strip of your JForex platform, and if that's getting too high,
that's part of your problem.

HyperScalper

Thanks for the ideas.

So have I!

I've been observing this bug for years and it doesn't feel like a heap space problem. My experience is that applications usually slow down a lot when heap space runs out as Java struggles to consolidate objects in the heap to make room for new allocations. This slowdown doesn't happen here. Everything about the application is fine and perfectly responsive - just that chart is somehow not receiving its ticks.

But I'll keep this in mind and look at the heap size next time it happens. Thanks!

I really hope Dukascopy can pin this down because its hugely annoying.

Some malfunctioning indicator on the chart?
Some malfunctioning strategy module?
Can't say I've ever seen such a problem...
I run 24x5 but you might have a large number of
charts or instruments or whatever....
If a Strategy is writing onto a chart and deadlocks
or something like that, could cause platform to
malfunction. If it dispathes using IContext.executeTask(task)
but that deadlocks, would probably block the entire platform's
gui, not just a single chart. An indicator that malfunctioned
might block a single chart? <speculation alert>
HyperScalper

There are no indicators on the chart.
I doubt it. I can't remember a particular case (and will keep in mind to observe in future),
but I think it has happened even without any running strategies. It just happens at random.
(What is 24x5?) When it happens I am usually only subscribed to 1 or 2 instruments,
and have only 2 or 3 charts open.
I will keep in mind and try to confirm whether it ever happens without any strategy running.
But then again, why would everything (and I mean everything - strategies, charts, everything)
continue as normal after I open a new chart?
Never does.
No indicators ever. My strategy calculates indicators internally.
Over the years I've come to believe quite strongly that its a bug that only appears when
the platform has a poor internet connection. There seems to be some correlation.
I am in South Africa. Some silent exceptions concerning connectivity sometimes appear in the Java Console.
(Note: the chart in question may not update for days after, even though other charts of the same instrument are updating.)

Thanks for your interest and ideas.
Isak

24x5 means running continuously 24 hours / day 5 days per week,
without restarts.
I run under the Java "Server VM" and make sure I have a liberal heap allocation.
HyperScalper

In the mean time I have confirmed observations 1 to 4 in the original post multiple times, and added observation 5.

I have confirmed that this bug can occur when the memory heap indicator shows that there is plenty of free space available on the heap (as in 95% free).

We cannot reproduce the issue.

Well, it is an intermittent bug, after all.
I can also confirm (after many verifications) that the 5 numbered observations listed in post #1 are consistent characteristics of the bug.

I have posted more information about this bug here, because nobody looks at "Fixed bugs".