'while' loop spins on field
Reports while
loops that spin on the value of a non-volatile
field, waiting for it to be changed by another thread.
In addition to being potentially extremely CPU intensive when little work is done inside the loop, such loops are likely to have different semantics from what was intended. The Java Memory Model allows such loops to never complete even if another thread changes the field's value.
Additionally, since Java 9 it's recommended to call Thread.onSpinWait()
inside a spin loop on a volatile
field, which may significantly improve performance on some hardware.
Example:
class SpinsOnField {
boolean ready = false;
void run() {
while (!ready) {
}
// do some work
}
void markAsReady() {
ready = true;
}
}
After the quick-fix is applied:
class SpinsOnField {
volatile boolean ready = false;
void run() {
while (!ready) {
Thread.onSpinWait();
}
// do some work
}
void markAsReady() {
ready = true;
}
}
- By ID
Can be used to locate inspection in e.g. Qodana configuration files, where you can quickly enable or disable it, or adjust its settings.
WhileLoopSpinsOnField
Use the inspection options to only report empty while
loops.
Here you can find the description of settings available for the 'while' loop spins on field inspection, and the reference of their default values.
Inspection Details | |
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By default bundled with: | |
Can be installed with plugin: | Java, 243.23126 |
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