Encountered a difficult SIGSEGV error using flowmon, traced back to nstime.h. Any suggestions appreciated.

[oleg...@gmail.com]

Hello, I have been using tracemetrics to analyze data of my script, now I want to try using Flow Monitor and I have encountered this problem, I've used Mr Konstantinos lab example http://personal.ee.surrey.ac.uk/Personal/K.Katsaros/media/ns3lab-sol/lab-2-solved.cc as it is very close to what I needed, but running both the example aswell as my script gives me this error, which I traced using gdb as adviced on ns wiki, gdb output is :

Program received signal SIGSEGV, Segmentation fault.

0x00007ffff7564ef2 in ns3::Time::Time (this=0x7fffffffce50, o=...

    at ./ns3/nstime.h:175

175    : m_data (o.m_data)

(gdb) where

#0  0x00007ffff7564ef2 in ns3::Time::Time (this=0x7fffffffce50, o=...)

    at ./ns3/nstime.h:175

#1  0x00007ffff40efdba in ns3::FlowMonitor::CheckForLostPackets (this=0x0)

    at ../src/flow-monitor/model/flow-monitor.cc:316

#2  0x00007ffff40f0174 in ns3::FlowMonitor::SerializeToXmlStream (this=0x0, 

    os=..., indent=0, enableHistograms=true, enableProbes=true)

    at ../src/flow-monitor/model/flow-monitor.cc:400

#3  0x00007ffff40f0ef0 in ns3::FlowMonitor::SerializeToXmlFile (this=0x0, 

    fileName=..., enableHistograms=true, enableProbes=true)

    at ../src/flow-monitor/model/flow-monitor.cc:492

#4  0x000000000040d946 in main (argc=1, argv=0x7fffffffdd68)

    at ../scratch/2323.cc:330

line 175 in ~/src/core/model/nstime.h looks like this 

174  inline Time(const Time &o)

175    : m_data (o.m_data)

176  {}

Looking in documentation I've found that m_data contains virtual time value, and my progress on resolving this bug stopped, I would appreciate any suggestion as to why is it occuring and what I can change about it. Thank you.

[Tommaso Pecorella]

Hi,

you're looking at the wrong point.

#3  0x00007ffff40f0ef0 in ns3::FlowMonitor::SerializeToXmlFile (this=0x0, 

    fileName=..., enableHistograms=true, enableProbes=true)

    at ../src/flow-monitor/model/flow-monitor.cc:492

#4  0x000000000040d946 in main (argc=1, argv=0x7fffffffdd68)

    at ../scratch/2323.cc:330

you're using a null pointer in your main at line 330.

T.

[oleg...@gmail.com]

Oh my, problem resolved. Thanks :)

четверг, 15 мая 2014 г., 10:51:29 UTC+3 пользователь Tommaso Pecorella написал:

[crea...@gmail.com]

hi~ I have a similar problem.Can you tell me how to solve this problem?Thanks

在 2014年5月15日星期四 UTC+8下午4:00:10，Олег Чабан写道：

[Tommaso Pecorella]

Hi,

no, you don't have a similar problem. Not more than anyone having a segmentation fault, which is more or less like saying that everyone feeling ill has the same illness.

No matter what, the solution is: learn to use a debugger.

T.