如何让LoadRunner中web_sync与轮询ResponseCB()不被计为浪费时间？

场景说明 #

针对异步web_url，LoadRunner新增了web_reg_async_attributes函数。我在Poll_0_ResponseCB中等待aHttpStatusCode == 200，因为该请求是XHR请求，服务器会异步传输所有数据，只有GET请求接收完所有数据后，事务才算完成。

现有代码 #

web_reg_async_attributes("ID=Poll_0", 
    "Pattern=Poll", 
    "URL=https://[URL]/api2/notifications/GetUnreadNotifications", 
    "PollIntervalMs=500", 
    "RequestCB=Poll_0_RequestCB", 
    "ResponseCB=Poll_0_ResponseCB", 
    LAST);
web_url("GetUnreadNotifications_2", 
    "URL=https://[URL]/api2/notifications/GetUnreadNotifications", 
    "Resource=0", 
    "RecContentType=application/json", 
    "Referer=https://[URL]/", 
    "Snapshot=t14.inf", 
    "Mode=HTML", 
    LAST);
web_sync("ParamCreated=stopAsync", "RetryIntervalMs=500", "RetryTimeoutMs=120000", LAST);
web_stop_async("ID=Poll_0",LAST);

当前问题 #

LoadRunner将上述轮询机制的时间计为浪费时间，但实际上这段等待是为了确保数据接收完成，需要将其纳入实际事务时长。当前运行结果示例：

ended with a "Pass" status (Duration: 33,9532 Wasted Time: 33,3178).

注：该API确实较慢...

解决方案 #

1. 手动用事务包裹完整流程 #

通过lr_start_transaction和lr_end_transaction直接包裹包含web_sync的整个关键流程，覆盖LoadRunner的自动计时逻辑，让工具将这段时间全部计入事务时长：

lr_start_transaction("GetUnreadNotifications_Transaction");

web_reg_async_attributes("ID=Poll_0", 
    "Pattern=Poll", 
    "URL=https://[URL]/api2/notifications/GetUnreadNotifications", 
    "PollIntervalMs=500", 
    "RequestCB=Poll_0_RequestCB", 
    "ResponseCB=Poll_0_ResponseCB", 
    LAST);
web_url("GetUnreadNotifications_2", 
    "URL=https://[URL]/api2/notifications/GetUnreadNotifications", 
    "Resource=0", 
    "RecContentType=application/json", 
    "Referer=https://[URL]/", 
    "Snapshot=t14.inf", 
    "Mode=HTML", 
    LAST);
web_sync("ParamCreated=stopAsync", "RetryIntervalMs=500", "RetryTimeoutMs=120000", LAST);
web_stop_async("ID=Poll_0",LAST);

lr_end_transaction("GetUnreadNotifications_Transaction", LR_AUTO);

2. 调整浪费时间识别配置 #

在LoadRunner的脚本设置中，找到「浪费时间」相关配置项，将web_sync操作的等待时间排除在浪费时间统计范围之外。不过这种方式是全局设置，可能会影响其他脚本的统计逻辑，适合所有web_sync等待都需计入事务的场景。

3. 自定义计时并关联事务 #

通过lr_start_timer和lr_end_timer获取这段流程的精确耗时，手动设置到事务中，实现更精细的时长控制：

double timer_start = lr_start_timer();

// 执行异步请求、同步等待、停止异步的完整代码块
web_reg_async_attributes("ID=Poll_0", 
    "Pattern=Poll", 
    "URL=https://[URL]/api2/notifications/GetUnreadNotifications", 
    "PollIntervalMs=500", 
    "RequestCB=Poll_0_RequestCB", 
    "ResponseCB=Poll_0_ResponseCB", 
    LAST);
web_url("GetUnreadNotifications_2", 
    "URL=https://[URL]/api2/notifications/GetUnreadNotifications", 
    "Resource=0", 
    "RecContentType=application/json", 
    "Referer=https://[URL]/", 
    "Snapshot=t14.inf", 
    "Mode=HTML", 
    LAST);
web_sync("ParamCreated=stopAsync", "RetryIntervalMs=500", "RetryTimeoutMs=120000", LAST);
web_stop_async("ID=Poll_0",LAST);

double total_duration = lr_end_timer();
lr_set_transaction_duration("GetUnreadNotifications_Transaction", total_duration);
lr_end_transaction("GetUnreadNotifications_Transaction", LR_AUTO);

内容的提问来源于stack exchange，提问作者kenneth