Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>First&amp;second questions - this code naturally exits because of the logic. Try adding a debug output here to see when producers quit. </p> <pre><code>if (data.size() == 3) { try { wait(); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } else { System.out.printf("%s: breaking as data size is %d, %d%n", Thread.currentThread().getName(), countofdata, data.size()); break; } </code></pre> <p>Another possible problem is: </p> <pre><code>for(int i = 0; i &lt; 3; i++){ data.PutData(); } </code></pre> <p>You put only three times into the queue.</p> <p>Hint: classy implementation of the producer-consumer problem in Java is i.e. <code>LinkedBlockingQueue</code>.</p> <p>Third question. I'll try to explain this with producers and consumers. Reader-writer problem is when you don't have producers, but have many consumers which access a single shared resource. Some of these can read the resource and some can write to the resource. Simultaneous reads are possible and the write lock is exclusive. </p> <p><strong>UPDATE</strong></p> <p>To emulate multiple reads, you may try using </p> <ul> <li><code>LinkedBlockingQueue</code> is a well-perfomant equivalent for your <code>DataStorage</code>.</li> <li><code>ReentrantReadWriteLock</code></li> <li>Or update your solution. This is study example and I didn't test, but should give you the general idea:</li> </ul> <pre>final Object readLock = new Object(); //use objects as locks final Object writeLock = new Object();</pre> <pre><code>public void GetData() { synchronized (readLock) { // acquire only the read lock while (data.isEmpty()) { try { wait(); } catch (InterruptedException e) { // TODO Auto-generated catch block } } double temp = (double) data.pop(); //System.out.println("Data poped out:" + temp); countofdata++; System.out.printf("%s: %d, %d%n", Thread.currentThread().getName(), countofdata, data.size()); notifyAll(); } } public void PutData() { synchronized (readLock) { //first, acquire the read lock synchronized (writeLock) { // then acquire the write lock while (true) { if (data.size() == 3) { try { wait(); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } else { System.out.printf("%s: breaking as data size is %d, %d%n", Thread.currentThread().getName(), countofdata, data.size()); break; } } double temp = Math.random(); data.push(temp); //System.out.println("Data inserted in storage:" + temp); countofdata--; notifyAll(); } } } </code></pre>
    singulars
    1. This table or related slice is empty.
    1. POJava multithreading queries on Producer Consumer application
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USAndrey Chaschev
    1. USAndrey Chaschev
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COStill I am confused about the answer of first two questions..When producer finds that data storage is full it should wait but here it is getting terminated! why? And Thanks for the answer of third question I got the concept :)..but then if I am using "synchronized" keyword in my program then how can I allow multiple reads at a time?
      singulars
      1. PO
      1. USNullpointer
    2. CO'synchronized' for the method means exclusive access on the `this` object. This is a very raw synch method and it is a bad smell when you have many of them for CPU-intensive parts of app which your queue is. So you won't be able to multiple read on a single data source from different threads. To do this you could... I'll update the answer.
      singulars
      1. PO
      1. USAndrey Chaschev
    3. COWell,Thanks for answer ...If I am asking for the readLock in every GetData() call then also only one reader can read the data i.e. the one who gets the readLock, write? How can multiple readers read the data? And PutData() part is working according to the algorithm :) Thanks again!
      singulars
      1. PO
      1. USNullpointer
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload