【高级技巧】协程超时兜底：resume与pcall的组合封装

local function makeWorker(items, batch)
    local co = coroutine.create(function()
        local done = 0
        for _, item in ipairs(items) do
            processItem(item)
            done = done + 1
            if done % batch == 0 then
                coroutine.yield(false, done)
            end
        end
        coroutine.yield(true, done)
    end)
    return co
end

local function runWithWatch(co, timeoutSec)
    while true do
        local start = os.time()
        local ok, finished, done = coroutine.resume(co)
        if not ok then
            print("协程出错：" .. tostring(finished))
            return false
        end
        if finished then
            print("完成，共 " .. done .. " 条")
            return true
        end
        if os.time() - start > timeoutSec then
            print("单批超时，协程僵死")
            return false
        end
    end
end