DocumentsWriterStallControl

java.lang.Object
- org.apache.lucene.index.DocumentsWriterStallControl

```
final class DocumentsWriterStallControl
extends java.lang.Object
```
Controls the health status of a DocumentsWriter sessions. This class used to block incoming indexing threads if flushing significantly slower than indexing to ensure the DocumentsWriters healthiness. If flushing is significantly slower than indexing the net memory used within an IndexWriter session can increase very quickly and easily exceed the JVM's available memory.
To prevent OOM Errors and ensure IndexWriter's stability this class blocks incoming threads from indexing once 2 x number of available DocumentsWriterPerThreads in DocumentsWriterPerThreadPool is exceeded. Once flushing catches up and the number of flushing DWPT is equal or lower than the number of active DocumentsWriterPerThreads threads are released and can continue indexing.

Field Summary

Fields
Modifier and Type	Field	Description
`private int`	`numWaiting`
`private boolean`	`stalled`
`private java.util.Map<java.lang.Thread,java.lang.Boolean>`	`waiting`
`private boolean`	`wasStalled`

Constructor Summary

Constructors
Constructor Description

DocumentsWriterStallControl()

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`(package private) boolean`	`anyStalledThreads()`
`private void`	`decrWaiters()`
`(package private) int`	`getNumWaiting()`
`(package private) boolean`	`hasBlocked()`
`private void`	`incWaiters()`
`(package private) boolean`	`isHealthy()`
`(package private) boolean`	`isThreadQueued(java.lang.Thread t)`
`(package private) void`	`updateStalled(boolean stalled)`	Update the stalled flag status.
`(package private) void`	`waitIfStalled()`	Blocks if documents writing is currently in a stalled state.
`(package private) boolean`	`wasStalled()`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - stalled
```
private volatile boolean stalled
```
  - numWaiting
```
private int numWaiting
```
  - wasStalled
```
private boolean wasStalled
```
  - waiting
```
private final java.util.Map<java.lang.Thread,java.lang.Boolean> waiting
```
- Constructor Detail
  - DocumentsWriterStallControl
```
DocumentsWriterStallControl()
```
- Method Detail
  - updateStalled
```
void updateStalled(boolean stalled)
```
    Update the stalled flag status. This method will set the stalled flag to true iff the number of flushing DocumentsWriterPerThread is greater than the number of active DocumentsWriterPerThread. Otherwise it will reset the DocumentsWriterStallControl to healthy and release all threads waiting on waitIfStalled()
  - waitIfStalled
```
void waitIfStalled()
```
    Blocks if documents writing is currently in a stalled state.
  - anyStalledThreads
```
boolean anyStalledThreads()
```
  - incWaiters
```
private void incWaiters()
```
  - decrWaiters
```
private void decrWaiters()
```
  - hasBlocked
```
boolean hasBlocked()
```
  - getNumWaiting
```
int getNumWaiting()
```
  - isHealthy
```
boolean isHealthy()
```
  - isThreadQueued
```
boolean isThreadQueued(java.lang.Thread t)
```
  - wasStalled
```
boolean wasStalled()
```