esp32 esp-idf v4.4.4 mongoose.ws 7.10 crashes during websocket update

[steff2000]

Hi folks,
my mongoose webserver appllication updates clients via websocket, so far so good.
Sometimes the application crashes with a Guru Meditation Error.

As I see it, the error only happens when another websocket client connects.
I think I have seen the error also when a disconnect (web browser window closed) occurs.

Guru Meditation Error: Core 1 panic'ed (LoadStoreError). Exception was unhandled.

Core 1 register dump:
PC : 0x4000c3f5 PS : 0x00060f30 A0 : 0x800e5efc A1 : 0x3ffd7fd0
A2 : 0x3ffe8c71 A3 : 0x3ffe8c67 A4 : 0xfffffded A5 : 0x0000000a
A6 : 0x3ffce604 A7 : 0x00000800 A8 : 0x0001738f A9 : 0x40000000
A10 : 0x00000000 A11 : 0x295a3860 A12 : 0x00000000 A13 : 0x3ffd67d0
A14 : 0x00000003 A15 : 0x00060023 SAR : 0x00000020 EXCCAUSE: 0x00000003
EXCVADDR: 0x40000000 LBEG : 0x400014fd LEND : 0x4000150d LCOUNT : 0xffffffdf

Backtrace: 0x4000c3f2:0x3ffd7fd0 0x400e5ef9:0x3ffd7ff0 0x400e5f52:0x3ffd8030 0x400e5f9a:0x3ffd8060 0x400db55b:0x3ffd80b0 0x40090f6a:0x3ffd8130
0x400e5ef9: mg_ws_wrap at /home/user/Dokumente/esp32_projekte/websocket_mqtt/main/mongoose.c:6325

0x400e5f52: mg_ws_vprintf at /home/user/Dokumente/esp32_projekte/websocket_mqtt/main/mongoose.c:6056

0x400e5f9a: mg_ws_printf at /home/user/Dokumente/esp32_projekte/websocket_mqtt/main/mongoose.c:6064

0x400db55b: WebSocketTask at /home/user/Dokumente/esp32_projekte/websocket_mqtt/main/WebSocketTask.c:98

0x40090f6a: vPortTaskWrapper at /home/user/Dokumente/esp-idf/components/freertos/port/xtensa/port.c:142

WebSocketTask,c:

                    [snip]
	        char *out = cJSON_Print(root);
		cJSON_Delete(root);
		for (c = mgr_p->conns; c != NULL; c = c->next) {
			if (c->data[0] != 'W') {
				continue;
			}

L98 size_t send = mg_ws_printf(c, WEBSOCKET_OP_TEXT, "%s", out);
} // for (c = mgr->conns; c != NULL; c = c->next)
free(out);
[snip]

[scaprile]

I can't guess what you are doing, nevertheless the word 'Task' above sends shivers down my spine.

From the docs

NOTE: Since Mongoose's core is not protected against concurrent accesses, make sure that all mg_* API functions are called from the same thread or RTOS task.

If you absolutely need multi-threading, take the time to go through the user guide (linked above) and tutorials, there is one that shows you how to do multi-threading.

If my guessing was wrong, please open an issue, fill the issue template, and provide the minimum piece of code to reproduce your issue.

[cpq]

@steff2000 Note: mongoose's *printf functions can print JSON. You don't need cJSON or any other JSON library.