在PHP中序列化一个大数组? [英] serialize a large array in PHP?

问题描述

我很好奇，在PHP中序列化是否有大小限制?可以对具有5,000个键和值的数组进行序列化，以便将其存储到缓存中吗?

I am curious, is there a size limit on serialize in PHP. Would it be possible to serialize an array with 5,000 keys and values so it can be stored into a cache?

我希望在社交网站上缓存用户的朋友列表，缓存需要进行相当频繁的更新，但是几乎每次加载页面时都需要读取缓存.

I am hoping to cache a users friend list on a social network site, the cache will need to be updated fairly often but it will need to be read almost every page load.

在单个服务器上，我假设APC会比内存缓存更好.

On a single server setup I am assuming APC would be better then memcache for this.

推荐答案

很多人已经回答了，只是为了好玩，这是一个非常快速的基准测试(我敢称呼它吗?);考虑以下代码:

As quite a couple other people answered already, just for fun, here's a very quick benchmark (do I dare calling it that ? ) ; consider the following code :

$num = 1;

$list = array_fill(0, 5000, str_repeat('1234567890', $num));

$before = microtime(true);
for ($i=0 ; $i<10000 ; $i++) {
    $str = serialize($list);
}
$after = microtime(true);

var_dump($after-$before);
var_dump(memory_get_peak_usage());

我正在PHP 5.2.6(与Ubuntu jaunty捆绑在一起的版本)上运行此代码.
而且，是的，只有值；没有钥匙;值非常简单:没有对象，没有子数组，只有字符串.

对于$num = 1，您会得到:

float(11.8147978783)
int(1702688)

对于$num = 10，您会得到:

float(13.1230671406)
int(2612104)

然后，对于$num = 100，您将获得:

And, for $num = 100, you get :

float(63.2925770283)
int(11621760)

因此，似乎数组中的每个元素越大，所需的时间就越长.但是，对于大100倍的元素，您所花费的时间不会长100倍...

So, it seems the bigger each element of the array is, the longer it takes (seems fair, actually). But, for elements 100 times bigger, you don't take 100 times much longer...

现在，使用50000个元素的数组，而不是5000个元素，这意味着这部分代码已更改:

Now, with an array of 50000 elements, instead of 5000, which means this part of the code is changed :

$list = array_fill(0, 50000, str_repeat('1234567890', $num));

使用$num = 1，您将获得:

float(158.236332178)
int(15750752)

考虑到花费1的时间，我将不会同时为$ num = 10或$ num = 100 ...

Considering the time it took for 1, I won't be running this for either $num = 10 nor $num = 100...

是的，当然，在实际情况下，您不会这样做10000次；因此，让我们尝试使用for循环的10次迭代.

Yes, of course, in a real situation, you wouldn't be doing this 10000 times ; so let's try with only 10 iterations of the for loop.

对于$num = 1:

float(0.206310987473)
int(15750752)

对于$num = 10:

float(0.272629022598)
int(24849832)

对于$num = 100:

float(0.895547151566)
int(114949792)

是的，这差不多是1秒-占用了相当多的内存^^
(不，这不是生产服务器:我在此开发机上有一个相当高的memory_limit ^^)

Yeah, that's almost 1 second -- and quite a bit of memory used ^^
(No, this is not a production server : I have a pretty high memory_limit on this development machine ^^ )

因此，最后要比那些数字短一些-是的，您可以让数字说出您想要的数字-我不会说有一个极限"就像PHP中的硬编码"一样，但是您最终将面临其中之一:

So, in the end, to be a bit shorter than those number -- and, yes, you can have numbers say whatever you want them to -- I wouldn't say there is a "limit" as in "hardcoded" in PHP, but you'll end up facing one of those :

• max_execution_time(通常在网络服务器上，时间不会超过30秒)
• memory_limit(在网络服务器上，muco通常不会超过32MB)
• 您的Web服务器将承受的负载:当那些大的serialize-loop之一正在运行时，它占用了我的CPU之一；如果您同时在同一页面上有多个用户，那么我想您会想象这将给您带来什么;-)
• 您的用户的耐心^^

• max_execution_time (generally, on a webserver, it's never more than 30 seconds)
• memory_limit (on a webserver, it's generally not muco more than 32MB)
• the load you webserver will have : while 1 of those big serialize-loop was running, it took 1 of my CPU ; if you are having quite a couple of users on the same page at the same time, I let you imagine what it will give ;-)
• the patience of your user ^^

但是，除非您真的要序列化大数据长数组，否则我不确定这有多重要...
并且您必须考虑使用该缓存的时间/CPU负载量可能会帮助您获得;-)

But, except if you are really serializing long arrays of big data, I am not sure it will matter that much...
And you must take into consideration the amount of time/CPU-load using that cache might help you gain ;-)

仍然，最好的了解方法是使用真实数据自己进行测试；-)

Still, the best way to know would be to test by yourself, with real data ;-)

您可能还想看看 Xdebug 在

And you might also want to take a look at what Xdebug can do when it comes to profiling : this kind of situation is one of those it is useful for!

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