C++新手，求教为啥程序跑起来的内存越用越多

[albert0yyyy]

感觉好像是哪个变量申请了内存没有释放，然后越用越多，大概 20-30 来个请求增加 0.1G 的内存，我没有 delete 一些指针的话，增加的更快。

程序主要是通过 socket 通信，用 c++进行目标检测的这段代码。

op 只学过 c++的基本语法，平时做深度学习 python 用的比较多，所以 c++这边可能会欠缺一点，只能说把一些 bug 修复了能跑起来的水平。其实也是拿着官方 demo 改的，参数直接构造了一个 fake command ，见笑了

#include "jetson-utils/videoSource.h"
#include "jetson-utils/videoOutput.h"
#include "jetson-utils/imageLoader.h"
#include "jetson-inference/detectNet.h"
#include "jetson-inference/objectTracker.h"
#include "cJSON.h"
#include "jetson-utils/Socket.h"
#include <signal.h>
#include <vector>
using namespace std;

struct PredObj
{
	float x1;
	float y1;
	float x2;
	float y2;
	float score;
	int classID;
	float width;
	float height;
	const char *classDesc;
};

bool signal_recieved = false;

void sig_handler(int signo)
{
	if (signo == SIGINT)
	{
		LogVerbose("received SIGINT\n");
		signal_recieved = true;
	}
}

int usage()
{
	printf("usage: detectnet [--help] [--network=NETWORK] [--threshold=THRESHOLD] ...\n");
	printf("                 input [output]\n\n");
	printf("Locate objects in a video/image stream using an object detection DNN.\n");
	printf("See below for additional arguments that may not be shown above.\n\n");
	printf("positional arguments:\n");
	printf("    input           resource URI of input stream  (see videoSource below)\n");
	printf("    output          resource URI of output stream (see videoOutput below)\n\n");

	printf("%s", detectNet::Usage());
	printf("%s", objectTracker::Usage());
	printf("%s", videoSource::Usage());
	printf("%s", videoOutput::Usage());
	printf("%s", Log::Usage());

	return 0;
}

int main(int argc, char **argv)
{

	/*
	 * parse command line
	 */
	commandLine cmdLine(argc, argv);

	if (cmdLine.GetFlag("help"))
		return usage();

	/*
	 * create detection network
	 */
	detectNet *net = detectNet::Create(cmdLine);

	if (!net)
	{
		LogError("detectnet:  failed to load detectNet model\n");
		return 1;
	}

	// parse overlay flags
	const uint32_t overlayFlags = detectNet::OverlayFlagsFromStr(cmdLine.GetString("overlay", "box,labels,conf"));

	Socket *socket = Socket::Create(SOCKET_TCP);
	if (!socket)
	{
		printf("failed to create socket\n");
		return 0;
	}

	// bind the socket to a local port
	if (!socket->Bind("0.0.0.0", 8899))
	{
		printf("failed to bind socket\n");
		return 0;
	}

	if (!socket->Accept(0))
	{
		printf("failed to accept socket\n");
		return 0;
	}
	printf("server is running\n");

	if (cmdLine.GetFlag("help"))
		return usage();

	/*
	 * attach signal handler
	 */
	if (signal(SIGINT, sig_handler) == SIG_ERR)
		LogError("can't catch SIGINT\n");

	/*
	 * create input stream
	 */

	while (true)
	{
		// receive a message
		uint8_t buffer[1024];
		uint32_t remoteIP;
		uint16_t remotePort;
		size_t bytes = socket->Recieve(buffer, sizeof(buffer), &remoteIP, &remotePort);
		if (bytes == 0)
		{
			printf("close client\n");
			return 0;
		}
		else
		{
			const char *receiveData = NULL;
			printf("received message: %s\n", buffer);
			cJSON *cjson_receive = cJSON_Parse((char *)buffer);
			receiveData = cJSON_Print(cjson_receive);
			printf("%s\n", receiveData);
			SAFE_DELETE(receiveData);

			// cJSON *fStickLat = cJSON_GetObjectItem(cjson_receive, "fStickLat");
			// double m_fStickLat = cJSON_GetNumberValue(fStickLat);
			// printf("%.10f\n", m_fStickLat);
			// printf("m_fStickLat: %.10f\n", m_fStickLat);
			cJSON *fpath = cJSON_GetObjectItem(cjson_receive, "fpath");
			char *m_fpath = cJSON_GetStringValue(fpath);
			printf("m_fpath: %s\n", m_fpath);

			// 检测到 socket 等于 shutdown ，关闭 socket
			if (strcmp((char *)buffer, "shutdown") == 0)
			{
				printf("shutting down\n");
				break;
			}
			char av1[] = "detectnet";
			char av2[] = "--network=ssd-mobilenet-v2";
			char av3[] = "./socket_example/test1.jpg";
			int len = strlen(m_fpath);
			char av3_2[len];
			strcpy(av3_2, m_fpath);
			// char *fake_argv[3] = {av1, av2, m_fpath};
			char *fake_argv[3] = {av1, av2, av3_2};
			commandLine cmdLine(3, fake_argv);
			printf("t1\n");
			cJSON_Delete(cjson_receive);
			// cJSON_Delete(fpath);

			// SAFE_DELETE(m_fpath);
			printf("t2\n");

			/*
			 * create input stream
			 */

			videoSource *input = videoSource::Create(cmdLine, ARG_POSITION(0));

			if (!input)
			{
				LogError("detectnet:  failed to create input stream\n");
				// return 1;
				continue;
			}

			/*
			 * create output stream
			 */
			videoOutput *output = videoOutput::Create(cmdLine, ARG_POSITION(1));

			if (!output)
			{
				LogError("detectnet:  failed to create output stream\n");
				// return 1;
				continue;
			}
			/*
			 * processing loop
			 */
			// while( !signal_recieved )
			//{
			//  capture next image
			uchar3 *image = NULL;
			int status = 0;

			input->Capture(&image, &status);

			// if (!input->Capture(&image, &status))
			// {
			// 	// if( status == videoSource::TIMEOUT )
			// 	// continue;

			// 	// break; // EOS
			// }

			// detect objects in the frame
			detectNet::Detection *detections = NULL;

			const int numDetections = net->Detect(image, input->GetWidth(), input->GetHeight(), &detections, overlayFlags);
			vector<PredObj> predObjList;

			if (numDetections > 0)
			{
				LogVerbose("%i objects detected\n", numDetections);

				for (int n = 0; n < numDetections; n++)
				{
					LogVerbose("\ndetected obj %i  class #%u (%s)  confidence=%f\n", n, detections[n].ClassID, net->GetClassDesc(detections[n].ClassID), detections[n].Confidence);
					LogVerbose("bounding box %i  (%.2f, %.2f)  (%.2f, %.2f)  w=%.2f  h=%.2f\n", n, detections[n].Left, detections[n].Top, detections[n].Right, detections[n].Bottom, detections[n].Width(), detections[n].Height());

					if (detections[n].TrackID >= 0) // is this a tracked object?
						LogVerbose("tracking  ID %i  status=%i  frames=%i  lost=%i\n", detections[n].TrackID, detections[n].TrackStatus, detections[n].TrackFrames, detections[n].TrackLost);

					PredObj predObj;
					predObj.x1 = detections[n].Left;
					predObj.y1 = detections[n].Top;
					predObj.x2 = detections[n].Right;
					predObj.y2 = detections[n].Bottom;
					predObj.score = detections[n].Confidence;
					predObj.classID = detections[n].ClassID;
					predObj.width = detections[n].Width();
					predObj.height = detections[n].Height();
					predObj.classDesc = net->GetClassDesc(detections[n].ClassID);
					predObjList.push_back(predObj);
				}
			}

			// predObjList to json
			cJSON *cjson_send = cJSON_CreateObject();
			cJSON *cjson_array = cJSON_CreateArray();
			for (int i = 0; i < predObjList.size(); i++)
			{
				cJSON *cjson_obj = cJSON_CreateObject();
				cJSON_AddNumberToObject(cjson_obj, "x1", predObjList[i].x1);
				cJSON_AddNumberToObject(cjson_obj, "y1", predObjList[i].y1);
				cJSON_AddNumberToObject(cjson_obj, "x2", predObjList[i].x2);
				cJSON_AddNumberToObject(cjson_obj, "y2", predObjList[i].y2);
				cJSON_AddNumberToObject(cjson_obj, "score", predObjList[i].score);
				cJSON_AddNumberToObject(cjson_obj, "classID", predObjList[i].classID);
				cJSON_AddNumberToObject(cjson_obj, "width", predObjList[i].width);
				cJSON_AddNumberToObject(cjson_obj, "height", predObjList[i].height);
				cJSON_AddStringToObject(cjson_obj, "classDesc", predObjList[i].classDesc);
				cJSON_AddItemToArray(cjson_array, cjson_obj);
			}
			cJSON_AddItemToObject(cjson_send, "predObjList", cjson_array);
			char *json_str = cJSON_Print(cjson_send);

			if (!socket->Send((void *)json_str, strlen(json_str), remoteIP, remotePort))
			{
				// printf("failed to send message\n");
				printf("client is disconnected\n");
				break;
			}
			printf("t3\n");
			//cJSON_Delete(cjson_send);
			cJSON_Delete(cjson_array);
			SAFE_DELETE(json_str);

			// render outputs
			if (false && output != NULL)
			{
				output->Render(image, input->GetWidth(), input->GetHeight());

				// update the status bar
				char str[256];
				sprintf(str, "TensorRT %i.%i.%i | %s | Network %.0f FPS", NV_TENSORRT_MAJOR, NV_TENSORRT_MINOR, NV_TENSORRT_PATCH, precisionTypeToStr(net->GetPrecision()), net->GetNetworkFPS());
				output->SetStatus(str);

				// check if the user quit
				// if( !output->IsStreaming() )
				// break;
			}

			// print out timing info
			net->PrintProfilerTimes();
			printf("t4\n");

			SAFE_DELETE(input);
			SAFE_DELETE(output);
			// SAFE_DELETE(image);

			//}
		}
	}
	/*
	 * destroy resources
	 */
	LogVerbose("detectnet:  shutting down...\n");

	SAFE_DELETE(net);

	LogVerbose("detectnet:  shutdown complete.\n");
	return 0;
}

[shuax]

你都知道你写的是 C++了，多用 RAII 自动释放啊，手动释放太难了。

[YsHaNg]

TL;DR 扔给 GPT 了
Yes, there are several memory leaks in the provided code. Let's go through them:

1. In the loop where you receive messages via the socket, you allocate memory for `receiveData` using `cJSON_Print`, but you don't free it. You should free it after you're done using it.

2. Similarly, you create a `cJSON` object using `cJSON_Parse`, but you don't free it using `cJSON_Delete`.

3. You allocate memory for `json_str` using `cJSON_Print`, but you don't free it after sending it over the socket.

4. You allocate memory for `input` and `output` inside the loop, but you don't free them before the next iteration of the loop. This can lead to memory leaks if `input` or `output` fail to initialize.

To fix these memory leaks:

- Free `receiveData` after its use with `SAFE_DELETE(receiveData)`.

- Delete the `cjson_receive` object using `cJSON_Delete` after its use.

- Free `json_str` after sending it over the socket.

- Delete `input` and `output` objects at the end of each iteration of the loop before reinitializing them.

Here's how you can do it:

```cpp
SAFE_DELETE(receiveData);
cJSON_Delete(cjson_receive);
SAFE_DELETE(json_str);
SAFE_DELETE(input);
SAFE_DELETE(output);
```

Place these lines at appropriate locations in your code to ensure memory allocated dynamically is properly deallocated.

[albert0yyyy]

@YsHaNg gpt 我问了，好像并不能解决.

有的指针释放了会报错提示已经释放过了，不能再次释放了。所以我就注释了一些会报错的释放操作

[albert0yyyy]

@shuax 我去看看 RAII ，感谢

[YsHaNg]

@albert0yyyy RAII+smart ptr 多用 auto 会让生活好很多

[albert0yyyy]

@YsHaNg #5 感谢，我去看看。

[watzds]

内存越用越多也正常啊，看能增加到多少

[hello2090]

你实在调不出来的话，code 一部分一部分的 comment 掉试呗

[bfjm]

1. 可以使用 valgrind 看看哪里会有内存泄漏
2. 看这个 cJSON 的情况是分配了内存，需要手动调用他的内存分配函数，你可以使用 RAII 封装一下
类似这种
```c++
class smart_ptr
{
smart_ptr(char *buffer)
{

}

~smart_ptr()
{

}

};


```

[bfjm]

class smart_ptr
{
smart_ptr(char *buffer)
{
cjson = cJSON_Parse((char *)buffer)
}

~smart_ptr()
{
cJSON_Delete(cjson_receive);
}
cJSON *cjson
};

@bfjm

[bfjm]

另外你先得了解清除，这里面谁分配了内存，（谁分配谁释放），分配的是堆内存还是栈内存，栈内存不用手动释放，堆内存需要手动释放

[bfjm]

我不太确定 cJSON *cjson_obj = cJSON_CreateObject(); 这里分配内存没有，这里会比较可疑

[sidyhe]

查代码比较难的话, 用 tcmalloc 检测泄露, 它会告诉你哪里的内存没有释放

[cnbatch]

单凭肉眼观察发现以下几个内存泄漏点，可能不完整：

第一个：
cJSON *cjson_receive = cJSON_Parse((char *)buffer);
一旦 if (strcmp((char *)buffer, "shutdown") == 0)这里 break 掉，后面的 cJSON_Delete(cjson_receive)就无法执行，内存就这样泄露掉了

第二个：
videoSource::Create()调用了两次，第一次问题不大，第二次处理不妥
原因同第一次。如果 input 创建成功但 output 创建失败，那么随后的 continue 会导致 input 指针内存泄漏。

第三个：
if (!socket->Send((void *)json_str, strlen(json_str), remoteIP, remotePort))
同理，break 之前未释放内存

建议上述内存分配都用智能指针包起来，必要时传递析构用的释放函数，就像这样：
std::unique_ptr<cJSON, decltype(cJSON_Delete)> cjson_receive{ cJSON_Parse((char *)buffer), cJSON_Delete };

[yolee599]

我的看法，基本和 14 楼的一致，补充一点 socket 还有很多地方没处理好，比如：
1. if (!socket) 的时候应该释放 net 再 return 。
2. if (!socket->Bind("0.0.0.0", 8899)) 的时候应该同时释放 net 和 socket 再 return 。
3. 下面所有的 return 同理。
4. 在程序结束的时候 socket 也应该关闭和释放。

input 和 output ，如果 input 分配成功了，但是 output 分配失败了，在 continue 之前要先释放掉 input 。
其实主要看这几个关键字是否正确处理了之前分配的内存就行：return/break/continue/goto 。

[albert0yyyy]

@watzds
@hello2090
@bfjm #9

@sidyhe
@cnbatch
@yolee599


谢谢各位哥哥们，学到了很多 C++的技巧，我去改改。回头给你们反馈

[nooneanyone]

你如果不差共享指针这点内存和调用性能，就用 shared_ptr make_shared 吧。不要自己 new delete