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<concept id="GUID-4A6DC7BC-4FE9-4557-8992-0EA5ACD59A4D" xml:lang="en"><title>EGL Multithreading

Requirements</title><shortdesc>This topic provides EGL implementers with information about the

EGL multithreading requirements on the Symbian platform.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

<p><b>Target audience</b>: Device creators.</p>

<section id="GUID-E44AB766-ED1D-49EC-8D74-AE141B2406E7"><title>Introduction</title><p>This

topic provides clarifications to the following sections of the EGL specification:</p><ul>

<li>2.3 Direct Rendering and Address Spaces</li>

<li>3.7 Rendering Context</li>

<li>3.7.3 Binding Contexts and Drawables</li>

</ul><p>For links to the relevant EGL specifications, see <xref href="GUID-A5914CFF-6F86-53E8-9928-36D3379835B1.dita">EGL

Interface Overview</xref>.</p></section>

<section id="GUID-9E17E402-DA10-4DC3-AB97-E03135310C28"><title>Number of threads

per process</title><p>An EGL implementation must support an unlimited number

of threads per process. On Symbian all threads within a process share the

same virtual address space. EGL objects that are used by multiple threads

in a process are therefore used within the address space in which they are

created, as required by the EGL specification. </p><p>With one exception,

all EGL functions and handles must be able to be used and shared

between all of the threads within the same process. The exception is the EGL

window surface as explained in <xref href="GUID-894AB487-C127-532D-852B-37CB0DEA1440.dita">Symbian-Specific

Behavior</xref>. </p><p>There is a graphics resource cost associated with

each additional thread that uses EGL. Typically only one thread within a process

uses EGL. While usage by eight threads within a process should be possible,

it is exceptional and has not been encountered in practice. Therefore you

may want to optimize your implementation for between one and eight threads.

 </p></section>

<section id="GUID-D379EFA3-D88B-4626-8F2C-18FF82BB0E47"><title>Number of current

contexts</title><p>An EGL implementation should not place arbitrary restrictions

on the number of contexts that can be made current, other than the restrictions

that are explicitly stated in the specification. For example, <codeph>eglMakeCurrent()</codeph> should

not fail with <codeph>EGL_BAD_ACCESS</codeph> when a client attempts to make

multiple OpenVG contexts current to separate threads, simply because the implementation

has a limit to the number of contexts that can be current at the same time. </p></section>

</conbody><related-links>

<link href="GUID-F094A9FA-D253-5D33-B625-A2AA0B1CE447.dita"><linktext>EGL Implementer's

Guide</linktext></link>

</related-links></concept>