net.socket:connect() - leaks memory on DNS lookup fail

[Toshik]

NodeMCU 0.9.5 build 20150213 powered by Lua 5.1.4

net.socket:connect() leaks memory when called by hostname and DNS query failed. Base leak is about 240 bytes per call.

Test case:

function TestDNSLeak()
     c=net.createConnection(net.TCP, 0)
     c:connect(80, "bad-name.tld")
     tmr.alarm(1, 3000, 0, function() print("hack socket close, MEM: "..node.heap()) c:close() end) -- socket timeout hack
     print("MEM: "..node.heap())
end

Now run TestDNSLeak() every 5 seconds (do it not too fast, to get timer executed):

TestDNSLeak()
MEM: 20288
> DNS retry 1!
DNS retry 2!
DNS retry 3!
DNS retry 4!
DNS Fail!
hack socket close, MEM: 20840
TestDNSLeak()
MEM: 19952
> DNS retry 1!
DNS retry 2!
DNS retry 3!
DNS retry 4!
DNS Fail!
hack socket close, MEM: 20608
TestDNSLeak()
MEM: 19672
> DNS retry 1!
DNS retry 2!
DNS retry 3!
DNS retry 4!
DNS Fail!
hack socket close, MEM: 20336
TestDNSLeak()
MEM: 19456
> DNS retry 1!
DNS retry 2!
DNS retry 3!
DNS retry 4!
DNS Fail!
hack socket close, MEM: 20160
TestDNSLeak()
MEM: 19208
> DNS retry 1!
DNS retry 2!
DNS retry 3!
DNS retry 4!
DNS Fail!
hack socket close, MEM: 19936
TestDNSLeak()
MEM: 19008
> DNS retry 1!
DNS retry 2!
DNS retry 3!
DNS retry 4!
DNS Fail!
hack socket close, MEM: 19704

[dvv]

It's not necessarily a leak as Lua performs garbage collection lazily.
Try calling collectgarbage("collect") before printing heap amount first. TIA

[Toshik]

@dvv I have ran into that issue - my DNS was dead and ESP drains all memory...

Anyway, even with garbage collector same issue:

function TestDNSLeak()
     c=net.createConnection(net.TCP, 0)
     c:connect(80, "bad-name.tld")
     tmr.alarm(1, 3000, 0, function() collectgarbage("collect") print("hack socket close, MEM: "..node.heap()) c:close() end) -- socket timeout hack
     print("MEM: "..node.heap())
end

> TestDNSLeak()
MEM: 20072
> DNS retry 1!
DNS retry 2!
DNS retry 3!
DNS retry 4!
DNS Fail!
hack socket close, MEM: 20696
TestDNSLeak()
MEM: 19736
> DNS retry 1!
DNS retry 2!
DNS retry 3!
DNS retry 4!
DNS Fail!
> hack socket close, MEM: 20464
TestDNSLeak()
MEM: 19488
> DNS retry 1!
DNS retry 2!
DNS retry 3!
DNS retry 4!
DNS Fail!
hack socket close, MEM: 20184
TestDNSLeak()
MEM: 19264
> DNS retry 1!
DNS retry 2!
DNS retry 3!
DNS retry 4!
DNS Fail!
hack socket close, MEM: 20000
TestDNSLeak()
MEM: 19072
> DNS retry 1!
DNS retry 2!
DNS retry 3!
DNS retry 4!
DNS Fail!
hack socket close, MEM: 19808

[mikewen]

This is related:
#189

If able to specify DNS servers, it would be helpful.
Google's DNS servers are much better than my local ISP's.

On Fri, Feb 20, 2015 at 4:59 AM, Toshik notifications@github.com wrote:

@dvv https://github.com/dvv I have ran into that issue - my DNS was
dead and ESP drains all memory...

Anyway, even with garbage collector same issue:

function TestDNSLeak()
c=net.createConnection(net.TCP, 0)
c:connect(80, "bad-name.tld")
tmr.alarm(1, 3000, 0, function() collectgarbage("collect") print("hack socket close, MEM: "..node.heap()) c:close() end) -- socket timeout hack
print("MEM: "..node.heap())
end

TestDNSLeak()
MEM: 20072
DNS retry 1!
DNS retry 2!
DNS retry 3!
DNS retry 4!
DNS Fail!
hack socket close, MEM: 20696
TestDNSLeak()
MEM: 19736
DNS retry 1!
DNS retry 2!
DNS retry 3!
DNS retry 4!
DNS Fail!
hack socket close, MEM: 20464
TestDNSLeak()
MEM: 19488
DNS retry 1!
DNS retry 2!
DNS retry 3!
DNS retry 4!
DNS Fail!
hack socket close, MEM: 20184
TestDNSLeak()
MEM: 19264
DNS retry 1!
DNS retry 2!
DNS retry 3!
DNS retry 4!
DNS Fail!
hack socket close, MEM: 20000
TestDNSLeak()
MEM: 19072
DNS retry 1!
DNS retry 2!
DNS retry 3!
DNS retry 4!
DNS Fail!
hack socket close, MEM: 19808

—
Reply to this email directly or view it on GitHub
#234 (comment)
.

[Suxsem]

I can reproduce this

[nodemcu]

try newest release latest

[UserXYZ]

This problem is still relevant, and I opened a new issue about it since I can't reopen this one...basically, the test used is the same like this here, and behaviour goes from full restart immediatelly, after a few dns retry/fail attempts or after some undefined time, like 10 minutes or more...