Code Correctness: Call to notify()

Java/JSP

Abstract

呼叫 notify() 時，無法清楚知道喚醒哪一項執行緒。

Explanation

藉由呼叫 notify()，無法指定要喚醒哪一項執行緒。

範例 1：在下列程式碼中，notifyJob() 呼叫 notify()。


public synchronized notifyJob() {
flag = true;
notify();
}
...
public synchronized waitForSomething() {
while(!flag) {
    try {
        wait();
    }
    catch (InterruptedException e)
    {
        ...
    }
}
...
}

在此案例中，開發者想要喚醒呼叫 wait() 的執行緒，但 notify() 可能會通知不同的執行緒，而不是預期中的執行緒。

References

[1] Sun Microsystems, Inc. Java Sun Tutorial - Concurrency

[2] Sun Microsystems, Inc. Java Sun Tutorial - Concurrency

[3] THI02-J. Notify all waiting threads rather than a single thread CERT

[4] Standards Mapping - CIS Azure Kubernetes Service Benchmark 1.0

[5] Standards Mapping - CIS Amazon Elastic Kubernetes Service Benchmark 5.0

[6] Standards Mapping - CIS Amazon Web Services Foundations Benchmark 1

[7] Standards Mapping - CIS Google Kubernetes Engine Benchmark normal

[8] Standards Mapping - Common Weakness Enumeration CWE ID 373

desc.structural.java.code_correctness_call_to_notify