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the VM has limited space where it can store CPU sample information. |
at a higher sampling rate, the space fills up and begins |
to overflow sooner than it would have if a lower sampling |
rate was used. |
this means that you might not have access to CPU samples |
from the beginning of the recorded profile, depending |
on whether the buffer overflows during the time of recording. |
a profile that was recorded with a lower sampling rate |
yields a more coarse-grained CPU profile with fewer samples. |
this affects your app’s performance less, |
but you might have access to less information about what |
the CPU was doing during the time of the profile. |
the VM’s sample buffer also fills more slowly, so you can see |
CPU samples for a longer period of app run time. |
this means that you have a better chance of viewing CPU |
samples from the beginning of the recorded profile. |
<topic_end> |
<topic_start> |
filtering |
when viewing a CPU profile, you can filter the data by |
library, method name, or UserTag. |
<topic_end> |
<topic_start> |
guidelines |
when looking at a call tree or bottom up view, |
sometimes the trees can be very deep. |
to help with viewing parent-child relationships in a deep tree, |
enable the display guidelines option. |
this adds vertical guidelines between parent and child in the tree. |
<topic_end> |
<topic_start> |
other resources |
to learn how to use DevTools to analyze |
the CPU usage of a compute-intensive mandelbrot app, |
check out a guided CPU profiler view tutorial. |
also, learn how to analyze CPU usage when the app |
uses isolates for parallel computing. |
<topic_end> |
<topic_start> |
using the memory view |
the memory view provides insights into details |
of the application’s memory allocation and |
tools to detect and debug specific issues. |
info note |
this page is up to date for DevTools 2.23.0. |
for information on how to locate DevTools screens in different IDEs, |
check out the DevTools overview. |
to better understand the insights found on this page, |
the first section explains how dart manages memory. |
if you already understand dart’s memory management, |
you can skip to the memory view guide. |
<topic_end> |
<topic_start> |
reasons to use the memory view |
use the memory view for preemptive memory optimization or when |
your application experiences one of the following conditions: |
<topic_end> |
<topic_start> |
basic memory concepts |
dart objects created using a class constructor |
(for example, by using MyClass()) live in a |
portion of memory called the heap. the memory |
in the heap is managed by the dart VM (virtual machine). |
the dart VM allocates memory for the object at the moment of the object creation, |
and releases (or deallocates) the memory when the object |
is no longer used (see dart garbage collection). |
<topic_end> |
<topic_start> |
object types |
<topic_end> |
<topic_start> |
disposable object |
a disposable object is any dart object that defines a dispose() method. |
to avoid memory leaks, invoke dispose when the object isn’t needed anymore. |
<topic_end> |
<topic_start> |
memory-risky object |
a memory-risky object is an object that might cause a memory leak, |
if it is not disposed properly or disposed but not GCed. |
<topic_end> |
<topic_start> |
root object, retaining path, and reachability |
<topic_end> |
<topic_start> |
root object |
every dart application creates a root object that references, |
directly or indirectly, all other objects the application allocates. |
<topic_end> |
<topic_start> |
reachability |
if, at some moment of the application run, |
the root object stops referencing an allocated object, |
the object becomes unreachable, |
which is a signal for the garbage collector (gc) |
to deallocate the object’s memory. |
<topic_end> |
<topic_start> |
retaining path |
the sequence of references from root to an object |
is called the object’s retaining path, |
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