You are viewing a plain text version of this content. The canonical link for it is here.
Posted to dev@tomcat.apache.org by Felipe Ebert <fe...@gmail.com> on 2015/01/21 20:14:59 UTC
Questions About Tomcat Exception Handling
Hello
I'm sorry that this mail is not a development issue itself, it is just a
question about Tomcat' exception handling. I was checking some mails at
Tomcat dev list and I found two interesting and contrasting responses
regarding exception handling: one is from Mark Thomas and another is from
Remy Maucherat:
Mark Thomas:
http://www.mail-archive.com/dev%40tomcat.apache.org/msg45180.html
Remy Maucherat:
http://www.mail-archive.com/dev%40tomcat.apache.org/msg10280.html
So, I just would like to understand why Tomcat don't care about those
generic catches patterns (catch Throwable or catch Exception) as Remmy said
in his mail, which contrasts with Mark comments. And also I would really
appreciate if anyone could give me some insights in the matter.
And lastly, I also would like to hear some comments about how frequent bugs
are reported in Tomcat mailing list and not in the Bugzilla. I know the
pattern is to use Bugzilla, but I saw some comments from Dr. Justin
Erenkrantz (from Apache team) discussing that there are a lot of important
bugs fixes only reported in Tomcat mailing list.
I would like to thank you for the time. Any response will be very important
to my research.
--
Felipe Ebert
Re: [OT] Questions About Tomcat Exception Handling
Posted by Felix Schumacher <fe...@internetallee.de>.
Am 22.01.2015 um 00:51 schrieb Rémy Maucherat:
> 2015-01-21 23:47 GMT+01:00 Christopher Schultz <chris@christopherschultz.net
>> :
>> To wit:
>>
>> 1. org.apache.catalina.servlets.DefaultServlet.Range.validate modifies
>> the value of the "end" member. That seems ... odd.
>>
>> 2. copyRange(InputStream, ServletOutputStream) returns IOException
>> instead of throwing it. There is one call to copyRange() that always
>> ignores this return value, even if it is a non-null IOException object.
>>
>> 3. executePartialPut(HttpServletRequest, Range, String) has a potential
>> resource leak of bufOldRevStream.
>>
>>
>> I'm not well-versed in the DefaultServlet to know if 1 and 2 are
>> legitimate, but they definitely smell funny. The resource issue in #3
>> should probably be fixed, and I'm happy to provide a fix for it.
>>
> Yes, it would be a good idea to be careful with 1 and 2.
I came along issue 2 while looking at a resource leak identified by
coverity scan in getReadme, which is the one method, which ignores the
returned exception. The comments in the other methods seem to indicate,
that a try/finally block plus a conversion to throwing the exception
instead of returning it in copyRange would be appropriate.
Regards
Felix
>
> I don't remember reading that article, but maybe I forgot.
>
> Rémy
>
---------------------------------------------------------------------
To unsubscribe, e-mail: dev-unsubscribe@tomcat.apache.org
For additional commands, e-mail: dev-help@tomcat.apache.org
Re: [OT] Questions About Tomcat Exception Handling
Posted by Rémy Maucherat <re...@apache.org>.
2015-01-21 23:47 GMT+01:00 Christopher Schultz <chris@christopherschultz.net
>:
> To wit:
>
> 1. org.apache.catalina.servlets.DefaultServlet.Range.validate modifies
> the value of the "end" member. That seems ... odd.
>
> 2. copyRange(InputStream, ServletOutputStream) returns IOException
> instead of throwing it. There is one call to copyRange() that always
> ignores this return value, even if it is a non-null IOException object.
>
> 3. executePartialPut(HttpServletRequest, Range, String) has a potential
> resource leak of bufOldRevStream.
>
>
> I'm not well-versed in the DefaultServlet to know if 1 and 2 are
> legitimate, but they definitely smell funny. The resource issue in #3
> should probably be fixed, and I'm happy to provide a fix for it.
>
Yes, it would be a good idea to be careful with 1 and 2.
I don't remember reading that article, but maybe I forgot.
Rémy
Re: [OT] Questions About Tomcat Exception Handling
Posted by Christopher Schultz <ch...@christopherschultz.net>.
Mark,
On 1/21/15 2:34 PM, Mark Thomas wrote:
> On 21/01/2015 19:14, Felipe Ebert wrote:
>> Hello
>>
>> I'm sorry that this mail is not a development issue itself, it is just a
>> question about Tomcat' exception handling. I was checking some mails at
>> Tomcat dev list and I found two interesting and contrasting responses
>> regarding exception handling: one is from Mark Thomas and another is from
>> Remy Maucherat:
>>
>> Mark Thomas:
>> http://www.mail-archive.com/dev%40tomcat.apache.org/msg45180.html
>>
>> Remy Maucherat:
>> http://www.mail-archive.com/dev%40tomcat.apache.org/msg10280.html
>
> The tone might be different but the response is pretty much the same: we
> don't view the issues reported as bugs.
>
>> So, I just would like to understand why Tomcat don't care about those
>> generic catches patterns (catch Throwable or catch Exception) as Remmy said
>> in his mail, which contrasts with Mark comments. And also I would really
>> appreciate if anyone could give me some insights in the matter.
>
> Again, I don't read the substance of our responses as being that different.
>
> Where these patterns are used they are used with good reason. If someone
> reports one that isn't backed with a good reason we'll fix it. The
> frustrating thing from our point of view is that most of the reports we
> receive along these lines are from people who clearly have zero
> understanding of the Tomcat code and are blindly reporting something
> some static analysis tool has reported.
>
> I'm not going to justify every single time we catch Throwable but a
> typical pattern is when calling user code that can (and often does)
> throw some random exception the only viable option when any error in
> user code needs handling (even if it is to simply ignore it) is to catch
> Throwable.
>
>> And lastly, I also would like to hear some comments about how frequent bugs
>> are reported in Tomcat mailing list and not in the Bugzilla. I know the
>> pattern is to use Bugzilla, but I saw some comments from Dr. Justin
>> Erenkrantz (from Apache team) discussing that there are a lot of important
>> bugs fixes only reported in Tomcat mailing list.
>
> Take a look at the change log. That will give you an idea of how many
> things get fixed that aren't in bugzilla. Whether it was originally
> reported via a mailing list isn't recorded. They will be a mix of
> mailing list, things committers spot at work and things committers spot
> while looking at the code for some other reason.
I read a post from 8 years ago from some guy who had a collection of bad
days until his whole collection of web sites went dead. Anyhow, here's
the link:
http://www.jroller.com/fate/entry/why_i_hate_tomcat
He basically defecates all over the DefaultServlet, and claims it's
representative of all of Tomcat's code. Granted, it was way back in
Tomcat 5.5 days and his form of invective is, as usual, neither
constructive nor completely coherent.
But he does have a few points, and I took a few minutes looking at the
DefaultServlet in the current trunk, and I think he made some fair
points about things that still exist.
To wit:
1. org.apache.catalina.servlets.DefaultServlet.Range.validate modifies
the value of the "end" member. That seems ... odd.
2. copyRange(InputStream, ServletOutputStream) returns IOException
instead of throwing it. There is one call to copyRange() that always
ignores this return value, even if it is a non-null IOException object.
3. executePartialPut(HttpServletRequest, Range, String) has a potential
resource leak of bufOldRevStream.
I'm not well-versed in the DefaultServlet to know if 1 and 2 are
legitimate, but they definitely smell funny. The resource issue in #3
should probably be fixed, and I'm happy to provide a fix for it.
The Coverity scan has been great at finding likely bugs and stuff... the
list is just enormous and it's tough to get through it all. I suspect #3
above is in that report, buried somewhere in the million potential
issues it has found.
-chris
Re: Questions About Tomcat Exception Handling
Posted by Mark Thomas <ma...@apache.org>.
On 21/01/2015 19:14, Felipe Ebert wrote:
> Hello
>
> I'm sorry that this mail is not a development issue itself, it is just a
> question about Tomcat' exception handling. I was checking some mails at
> Tomcat dev list and I found two interesting and contrasting responses
> regarding exception handling: one is from Mark Thomas and another is from
> Remy Maucherat:
>
> Mark Thomas:
> http://www.mail-archive.com/dev%40tomcat.apache.org/msg45180.html
>
> Remy Maucherat:
> http://www.mail-archive.com/dev%40tomcat.apache.org/msg10280.html
The tone might be different but the response is pretty much the same: we
don't view the issues reported as bugs.
> So, I just would like to understand why Tomcat don't care about those
> generic catches patterns (catch Throwable or catch Exception) as Remmy said
> in his mail, which contrasts with Mark comments. And also I would really
> appreciate if anyone could give me some insights in the matter.
Again, I don't read the substance of our responses as being that different.
Where these patterns are used they are used with good reason. If someone
reports one that isn't backed with a good reason we'll fix it. The
frustrating thing from our point of view is that most of the reports we
receive along these lines are from people who clearly have zero
understanding of the Tomcat code and are blindly reporting something
some static analysis tool has reported.
I'm not going to justify every single time we catch Throwable but a
typical pattern is when calling user code that can (and often does)
throw some random exception the only viable option when any error in
user code needs handling (even if it is to simply ignore it) is to catch
Throwable.
> And lastly, I also would like to hear some comments about how frequent bugs
> are reported in Tomcat mailing list and not in the Bugzilla. I know the
> pattern is to use Bugzilla, but I saw some comments from Dr. Justin
> Erenkrantz (from Apache team) discussing that there are a lot of important
> bugs fixes only reported in Tomcat mailing list.
Take a look at the change log. That will give you an idea of how many
things get fixed that aren't in bugzilla. Whether it was originally
reported via a mailing list isn't recorded. They will be a mix of
mailing list, things committers spot at work and things committers spot
while looking at the code for some other reason.
Mark
---------------------------------------------------------------------
To unsubscribe, e-mail: dev-unsubscribe@tomcat.apache.org
For additional commands, e-mail: dev-help@tomcat.apache.org