Transaction exceeded the current CPU usage limit imposed on the transaction

最近链发送交易过大时容易发生一下错误

{
    "message": "Internal Service Error",
    "code": "500",
    "error": {
        "code": "3080004",
        "name": "tx_cpu_usage_exceeded",
        "what": "Transaction exceeded the current CPU usage limit imposed on the transaction",
        "details": [{
            "message": "transaction was executing for too long",
            "file": "transaction_context.cpp",
            "line_number": 488,
            "method": "checktime"
        }, {
            "message": "pending console output: ",
            "file": "apply_context.cpp",
            "line_number": 113,
            "method": "exec_one"
        }]
    }
}

根据错误信息，定位源代码位置 （github）

由于now > _deadline并且 deadline_exception_code == tx_cpu_usage_exceeded::code_value 走到此断言逻辑
倒推到函数调用位置（github）

checktime(); // Fail early if deadline has already been exceeded

提示信息为：如果已超过截止日期，则提早失败
继续反推代码
由于（github）交易组装时trx.max_cpu_usage_ms固定设置的0。所以，判断逻辑出自（github）

// Possibly lower objective_duration_limit to the maximum cpu usage a transaction is allowed to be billed
if( cfg.max_transaction_cpu_usage <= objective_duration_limit.count() ) {
    objective_duration_limit = fc::microseconds(cfg.max_transaction_cpu_usage);
    billing_timer_exception_code = tx_cpu_usage_exceeded::code_value;
    _deadline = start + objective_duration_limit;
}

auto& rl = control.get_mutable_resource_limits_manager();
objective_duration_limit = fc::microseconds( rl.get_block_cpu_limit() );
_deadline = start + objective_duration_limit;
if(now > _deadline) {
    // 报异常
}

get_mutable_resource_limits_manager（github）

resource_limits_manager&         controller::get_mutable_resource_limits_manager()
{
   return my->resource_limits;
}

get_block_cpu_limit（github）

uint64_t resource_limits_manager::get_block_cpu_limit() const {
   const auto& state = _db.get<resource_limits_state_object>();
   const auto& config = _db.get<resource_limits_config_object>();
   return config.cpu_limit_parameters.max - state.pending_cpu_usage;
}

跟进停止

发现是由于合约中使用了std::vector<std::string> 持续存储大量数据，导致单次CPU运算执行耗时持续增长。

结论

当合约中Table单条记录中，如果使用vector不要存储过多数据，以及数据结构过于复杂的struct。
如有对应需求，可以拆分子表，然后使用子表记录id索引对应。