Date: Tue, 27 Dec 2016 11:09:47 -0800 From: Alfred Perlstein <alfred@freebsd.org> To: Xin LI <delphij@gmail.com> Cc: =?utf-8?B?55ub5oWn5Y2O?= <hhsheng@corp.netease.com>, Hongjiang Zhang <honzhan@microsoft.com>, freebsd-arch@freebsd.org, Jilles Tjoelker <jilles@stack.nl> Subject: Re: question about fopen fd limit Message-ID: <5461BE82-34CF-4B46-B7A1-6F8E1B3246C8@freebsd.org> In-Reply-To: <CAGMYy3tQ0=7wEegf0W6Fq-Av%2BDTquc0su7Eg8o4OfEAmq3rCrg@mail.gmail.com> References: <2016122223570929089978@corp.netease.com> <CY1PR03MB1517A33F8F9E0BAC00C2E345B5950@CY1PR03MB1517.namprd03.prod.outlook.com> <2016122311014089280414@corp.netease.com> <CY1PR03MB151796BFAEA5DDB1CD6DB752B5950@CY1PR03MB1517.namprd03.prod.outlook.com> <2016122316484066524625@corp.netease.com> <db32b02b-2eb3-cee8-98cd-0940223f04d9@freebsd.org> <CAGMYy3tQ0=7wEegf0W6Fq-Av%2BDTquc0su7Eg8o4OfEAmq3rCrg@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
Makes sense, at the same time if we go to 4/2billion descriptors it shouldn'=
t matter. Another trick would be to augment the inline function to check a v=
ersion flag and if it's incorrect then call the libc function. This will cau=
se some performance problems but only for really old software.=20
Sent from my iPhone
> On Dec 27, 2016, at 9:52 AM, Xin LI <delphij@gmail.com> wrote:
>=20
> -freebsd-net (bcc), +freebsd-arch
>=20
> This would work but also comes with a lot of pain.
>=20
> (But really - why do we implement these accessors, like fileno() and frien=
ds as macros with knowledge of the sFILE layout? Will it be reasonable to s=
tart converting these to functions as a first step, which would not break AB=
I but allow us to do it in the future? Otherwise we would be just kicking t=
he same can along the street forever...)
>=20
> FILE is supposed to be fully opaque to application writers in my opinion.
>=20
>> On Sat, Dec 24, 2016 at 5:19 PM, Alfred Perlstein <alfred@freebsd.org> wr=
ote:
>> Hello =E7=9B=9B=E6=85=A7=E5=8D=8E
>>=20
>> Here's another trick that may work.
>>=20
>> Use funopen(3) and provide your own read/write/seek and close functions f=
or the high fds.
>>=20
>> You can basically make "cookie" a struct that contains your "int sized" f=
ds.
>>=20
>> FILE *
>> funopen(const void *cookie, int (*readfn)(void *, char *, int), int (=
*writefn)(void *, const char *, int),
>> fpos_t (*seekfn)(void *, fpos_t, int), int (*closefn)(void *));
>>=20
>>=20
>> If you need more help please make sure to email me directly so I can see y=
our question.
>>=20
>> -Alfred
>>=20
>>=20
>>=20
>>> On 12/23/16 12:48 AM, =E7=9B=9B=E6=85=A7=E5=8D=8E wrote:
>>> hi all,
>>>=20
>>> Thank you for your advice ~
>>> solution 2 definitly broaden my horizons ~~but may be not a good choic=
e for my project ~~LoL
>>> i will try to mail freebsd-current mail list, if libc is as your descri=
ption , may be i should modify it by myself ~~
>>> Thank you so much~
>>> Are u KingSoft's Dr Zhang ? nice to meet you !!!!!
>>>=20
>>> =
winson sheng
>>> =20
>>>=20
>>> winson sheng
>>> From: Hongjiang Zhang
>>> Date: 2016-12-23 11:44
>>> To: =E7=9B=9B=E6=85=A7=E5=8D=8E; freebsd-net
>>> Subject: RE: RE: question about fopen fd limit
>>> Ok. I know.
>>> There are two possible solutions:
>>> Quick solution for short term: modify short to int in libc by yourself, b=
uildworld and installworld. Pushing to modify libc may take a long time, esp=
ecially only few people encounter this issue. You=E2=80=99d better send emai=
l to freebsd-current to confirm whether they accept your suggestion.
>>> Work around: You can first reserve a series of fd before opening TCP con=
nections. For example, invoke open(=E2=80=9C/dev/null=E2=80=9D) for 10000 ti=
mes to get 10000 fds. Those fd values are small enough to be held by =E2=80=9C=
short=E2=80=9D. After that, start TCP connections. Once you need to fopen a f=
ile, please call open(=E2=80=9Cxxx=E2=80=9D) instead, and then use dup2(old_=
fd, new_fd) to exchange the two fd. The old_fd value is the one obtained by o=
pen(=E2=80=9Cxxx=E2=80=9D), and new_fd is one in your reserved fd fields, an=
d next please use fdopen(fd, mode). Here, you have to manage the reserved fd=
s by yourself including open/close.
>>> In my eyes:
>>> is the quick method, and there is no modifications in your logic.
>>> Needs you to maintain the reserved consecutive fields for fd by yourself=
, which increased the complexity of your logic.
>>> Thanks
>>> Hongjiang Zhang
>>> From: =E7=9B=9B=E6=85=A7=E5=8D=8E [mailto:hhsheng@corp.netease.com]
>>> Sent: Friday, December 23, 2016 11:02 AM
>>> To: Hongjiang Zhang <honzhan@microsoft.com>; freebsd-net <freebsd-net@fr=
eebsd.org>
>>> Subject: Re: RE: question about fopen fd limit
>>> hi all,
>>> not map TCP to FILE, you misunderstanding my meaning~
>>> for example, if my server tcp already holds 32000 connection
>>> fopen only has 767 fd to use
>>> the problem has no bussiness with tcp fd, BUT fopen ...
>>> in some particular situlations , my server will open 1k+ FILE , tha=
t will exceed the fileno limit, and overflow occur
>>> my server can't open any file more ,that's the problem ~
>>> so i felt if bsd official could change FILE struct's fileno to a UN=
SIGNED SHORT that may be an effecient and convenient solution just for my ca=
se ?
>>> UNSIGNED SHORT fileno is enough for me, and i don't wanna change a lo=
t of FILE function that take FILE * as its argument ~
>>> Thank you ~~~
>>> winson sheng
>>> =20
>>>=20
>>> winson sheng
>>> From: Hongjiang Zhang
>>> Date: 2016-12-23 10:17
>>> To: =E7=9B=9B=E6=85=A7=E5=8D=8E; freebsd-net
>>> Subject: RE: question about fopen fd limit
>>> Why do you need to map TCP fd to FILE?
>>> It is difficult to modify FILE structure. If it is possible, let us fi=
gure out some new designs to meet your requirement.
>>> -----Original Message-----
>>> From: owner-freebsd-net@freebsd.org [mailto:owner-freebsd-net@freebsd.or=
g] On Behalf Of ???
>>> Sent: Thursday, December 22, 2016 11:57 PM
>>> To: freebsd-net <freebsd-net@freebsd.org>
>>> Subject: question about fopen fd limit
>>> hi all,
>>> hi~
>>> we are from Chinese Game Develop Corp, Netease.
>>> and One of our product using FreeBsd as its OS platform.
>>> This Game has Millions of players online , and Each Server may holds=
25000+ tcp connection at the same time.Thanks to BSD and kqueue :)
>>> for example, it's one of our server , netstat cmd to list connecti=
ons overall...
>>> netstat -an | grep 13396 (it's our listening port) | wc -l
>>> 23221
>>> recently we do some performance optimize and promote this connect=
limit to 28000+ or 30000+.
>>> But we find Freebsd has a limit that this huge online number will tak=
e 28000+ fd, and bsd FILE * struct's
>>> fd only support to SHORT . such as ..
>>> struct __sFILE {
>>> ...
>>> short _file; /* (*) fileno, if Unix descriptor, else -1 */ ...
>>> so if our server want to fopen some file when we still hold this on=
line number, the fd amount may easily exceed 32767, and fopen definitely ret=
urn a err code. then the server will appear some fataly ERROR.
>>> we do a simple test and confirm this situation.
>>> then in fopen's code , we notice that we can use open to return a f=
d instread of fopen to avoid this overflow,
>>> as below
>>> 68 /*
>>> 1 * File descriptors are a full int, but _file is only a short.
>>> 2 * If we get a valid file descriptor that is greater than
>>> 3 * SHRT_MAX, then the fd will get sign-extended into an
>>> 4 * invalid file descriptor. Handle this case by failing the
>>> 5 * open.
>>> 6 */
>>> BUT ... so many c lib FILE series function needs a FILE * pointer=
as input argument, we can't convert all of them to fd, or it will be a rath=
er suffering things to us.
>>> and even in BSD 10 , it seems this short limit still there , but ot=
her OS as debian , FILE strucnt's fileno is a int .
>>> we found an unoffical patch easily change this fileno to unsigned ,=
but we are a very stready project, we can't afford the risk to use an unoff=
ical patch.
>>> so, do you have any plan to change this fopen fd limit to UNSIGNED S=
HORT or int in the future ? ushort is enough for us .
>>> if you do , we are really glad and excited~~~~~~~if you don't ,it don=
en't matter, plz give us a reply so that we may need to
>>> find some other plan to resolved this suffering thing.
>>> LoL, thank you !!!!!
>>> yours sincerely
>>> winson sheng
>>> winson sheng
>>> _______________________________________________
>>> freebsd-net@freebsd.org mailing list
>>> https://na01.safelinks.protection.outlook.com/?url=3Dhttps%3A%2F%2Flists=
.freebsd.org%2Fmailman%2Flistinfo%2Ffreebsd-net&data=3D02%7C01%7Chonzhan%40m=
icrosoft.com%7C4a9dfccbccd446be2f4a08d42a833fb0%7C72f988bf86f141af91ab2d7cd0=
11db47%7C1%7C0%7C636180190584478890&sdata=3DPAwJP5IXHy0WJwxbV7MB%2B8zvKheZUY=
jhHx3ohFRSPZM%3D&reserved=3D0
>>> To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org"
>>> _______________________________________________
>>> freebsd-net@freebsd.org mailing list
>>> https://lists.freebsd.org/mailman/listinfo/freebsd-net
>>> To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org"
>>=20
>> _______________________________________________
>> freebsd-net@freebsd.org mailing list
>> https://lists.freebsd.org/mailman/listinfo/freebsd-net
>> To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org"
>=20
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?5461BE82-34CF-4B46-B7A1-6F8E1B3246C8>