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内存优化总结:ptmalloc、tcmalloc和jemalloc - 操作系统(内核) - 清泛网 - ...
... 总共32个vcpu。 16个table，每个5M row。
OLTP_RO测试包含5个select查询：select_ranges, select_order_ranges, select_distinct_ranges, select_sum_ranges,
可以看到在多核心或者多线程的场景下， jemalloc和tcmalloc带来的tps增加非常明显。
参考资料
glibc...
Is there a way to list open transactions on SQL Server 2000 database?
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For all databases query sys.sysprocesses
SELECT * FROM sys.sysprocesses WHERE open_tran = 1
For the current database use:
DBCC OPENTRAN
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Get “Value” property in IGrouping
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For any selected group,you could call
var selectedGroupValues=selectedGroup.SelectMany(x=>x);
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How can I deploy an iPhone application from Xcode to a real iPhone device?
...w the use of this certificate:
Launch Keychain Access.app. With no items selected, from the Keychain menu select Certificate Assistant, then Create a Certificate.
Name: iPhone Developer
Certificate Type: Code Signing
Let me override defaults: Yes
Click Continue
Validity: 3650 days
Click Cont...
What Vim command(s) can be used to quote/unquote words?
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Change single quotes to double quotes
va':s/\%V'\%V/"/g
va' - Visually select the quoted word and the quotes.
:s/ - Start a replacement.
\%V'\%V - Only match single quotes that are within the visually selected region.
/"/g - Replace them all with double quotes.
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@Override is not allowed when implementing interface method
...In JIdea 2020.1.2 and above,
Go to Project Structure [ Ctrl+Alt+Shift+S
]
Select Modules sub section
Select each module
Under sources-section, check Language Level
Change the Language Level as required
NOTE:
If you get below error after this change,
Error:java: Compilation failed: internal java c...
Javascript: How to loop through ALL DOM elements on a page?
... // Do something with the element here
}
Note that you could use querySelectorAll(), if it's available (IE9+, CSS in IE8), to just find elements with a particular class.
if (document.querySelectorAll)
var clsElements = document.querySelectorAll(".mySpeshalClass");
else
// loop through a...
Xcode 6 iPhone Simulator Application Support location
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in the top bar select: Product -> Archive -> and then Export the Archive as a Mac Application without re-signing (the last option) you will get a .app file which you can put in your Application folder like a normal application...
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Algorithm to return all combinations of k elements from n
... takes an array of letters as an argument and a number of those letters to select.
71 Answers
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Eclipse: enable assertions
...to Preferences.
Choose Java, and then Installed JREs from the left panel.
Select your JRE, and then click the Edit... button in the right panel.
In the Default VM arguments field, add -ea.
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