ThreadGuard
此類別僅適用於 Java Binding
ThreadGuard 檢查驅動程式是否僅從建立它的同一個執行緒呼叫。執行緒問題，尤其是在平行執行測試時，可能會產生神秘且難以診斷的錯誤。使用此包裝器可防止此類錯誤，並在發生時引發例外。
以下範例模擬執行緒衝突
public class DriverClash {
//thread main (id 1) created this driver
private WebDriver protectedDriver = ThreadGuard.protect(new ChromeDriver());
static {
System.setProperty("webdriver.chrome.driver", "<Set path to your Chromedriver>");
}
//Thread-1 (id 24) is calling the same driver causing the clash to happen
Runnable r1 = () -> {protectedDriver.get("https://selenium.programming.tw");};
Thread thr1 = new Thread(r1);
void runThreads(){
thr1.start();
}
public static void main(String[] args) {
new DriverClash().runThreads();
}
}
下方顯示的結果
Exception in thread "Thread-1" org.openqa.selenium.WebDriverException:
Thread safety error; this instance of WebDriver was constructed
on thread main (id 1)and is being accessed by thread Thread-1 (id 24)
This is not permitted and *will* cause undefined behaviour
如範例所示
protectedDriver將在主執行緒中建立- 我們使用 Java
Runnable來啟動新程序和新的Thread來執行程序 - 兩個
Thread將會衝突，因為主執行緒的記憶體中沒有protectedDriver。 ThreadGuard.protect將拋出例外。
注意
這不能取代在平行執行時使用 ThreadLocal 來管理驅動程式的需求。
