Clients

You can use the Clients menu item to monitor all the clients that are connected to your Hazelcast cluster.

Client Grid View

Table 1. Clients fields
Field	Description
Name	Name of the client instance.
Address	Local IP address, hostname, or canonical hostname of the client, depending on the client address filter.
Type	Type of client. This field typically denotes the client’s programming language and indicates whether it is an Enterprise Java client. Although non-Java clients can also connect to Enterprise clusters, the Java client includes Enterprise features that non-Java clients do not.
Routing Mode	Routing mode of the client. This field shows the routing mode that the client uses to connect to the cluster. All Members means a client is configured to allow connections to all members of a cluster, although the client might not be connected to them all. Single Member means a client is configured to connect only to a single member of the cluster. Multiple Members means that a client is configured to connect to a subset of the cluster members.
Connected Members	The members that the client is currently connected to. This field might show the address of the member, if the client is currently connected only to a single member, All Members if the client is connected to all members of the cluster, and shows number of currently connected members / total members, if the client is currently connected to a subset of members.
Hazelcast Client Version	Version of the client codebase.
UUID	Universally unique identifier of the client.
Labels	Any labels given to the client. You can use these labels to create filter lists that allow or deny the client’s connections to the cluster. See Managing Client Connections.

Available Data

By default, only basic information about connected clients is displayed. The values for other fields are shown as N/A.

To see all available information about a connected client in Management Center, the client must have the hazelcast.client.statistics.enabled system property set to true. See Client System Properties in the Platform documentation. This property configures clients to send statistics to the cluster, which in turn, sends them to Management Center.

To configure how often client statistics are collected, use the system property hazelcast.client.statistics.period.seconds.

MC-Client

All clusters have an entry for a client called MC-Client-<your cluster name>. This is the Management Center client that is connected to your cluster. Management Center uses this client to receive data from the cluster as well as send requests to it for operations such as shutting down members.

You cannot view any more details about this client other than what is displayed on the Clients page.

The MC-Client is not included in the client count that is displayed in the left-hand menu and the Cluster Connections page

Client Address Types

By default, the hostname of the client is displayed in the Address column.

To display the client’s IP address or the canonical hostname, use the Address Type dropdown.

Filtering Clients

To filter the displayed clients, use the Search bar in the right-hand corner.

To sort the table, click on the column headers.

Viewing Details about a Connected Client

Click on a client name will open a new page for monitoring that client on the right, as shown below.

Monitoring Client Detailed

Heap Memory Utilization

The Heap Memory Utilization chart shows the memory usage on the selected client with three different metrics (maximum, used and total memory) represented by different colors. You can open this chart as a separate window using the maximize button placed at top right of it.

General

General is a dynamically updated window tab showing general information about the client. Below are brief explanations for each piece of information:

Table 2. General client statistics
Field	Description
Name	Name of the client instance.
Address	Local IP address, hostname, or canonical hostname of the client, depending on the client address filter.
Type	Type of client. This field usually contains the client’s programming language.
Enterprise	Whether the client is an Enterprise Java client. Although non-Java clients can also connect to Enterprise clusters, the Java client includes Enterprise features that non-Java clients do not.
Routing Mode	Routing mode of the client. This can be Single Member, Multiple Members, or All Members.
Connected Members	The members that the client is currently connected to. This field might show the address of the member, if the client is currently connected only to a single member, All Members if the client is connected to all members of the cluster, and shows number of currently connected members / total members, if the client is currently connected to a subset of members. If the client is connected to a subset of members, select the icon next to the field to see the list of connected members.
Version	Version of the client codebase.
Last Connection to Cluster	Date and time that the client last connected to the cluster. This field is reset after each reconnection.
Last Statistics Collection	Date and time that statistics were last collected from the client.

Runtime

Next to the General tab, the Runtime tab shows the following values, which are collected from the default MXBeans in the Java Virtual Machine (JVM).

Some of these statistics may not be available for your client’s JVM implementation or operating system. N/A is shown for these types of statistics. Please refer to your JVM or operating system documentation for further details.

Table 3. Client runtime statistics
Field	Description
Number of Processors	Number of processors available to the client.
Uptime	Uptime of the client.
Maximum Memory	Maximum amount of memory that the client will attempt to use.
Total Memory	Amount of total heap memory currently available for current and future objects in the client.
Free Memory	Amount of free heap memory in the client.
Used Memory	Amount of used heap memory in the client.

OS

Next to the Runtime tab, the OS tab shows statistics about the operating system of the client. These values are collected from the default MXBeans in the Java Virtual Machine (JVM).

Table 4. Client operating system statistics
Field	Description
Free Physical Memory	Amount of free physical memory on the client device.
Committed Virtual Memory	Amount of virtual memory that is guaranteed to be available to the running process.
Total Physical Memory	Total amount of physical memory on the client device.
Free Swap Space	Amount of free swap space, which is used when the amount of physical memory (RAM) is full. If the system needs more memory resources and the RAM is full, inactive pages in memory are moved to the swap space.
Total Swap Space	Total amount of swap space.
Maximum File Descriptor Count	Maximum number of file descriptors, which is an integer that uniquely represents an opened file in the operating system.
Open File Descriptor Count	Number of open file descriptors.
Process CPU Time	CPU time used by the process on which the member (JVM) is running.
System Load Average	System load average for the last minute. The system load average is the average over a period of time of this sum: `(the number of runnable entities queued to the available processors) + (the number of runnable entities running on the available processors)` The way in which the load average is calculated is differently, depending on the operating system, but it is typically a damped time-dependent average.

Client Near Cache Statistics

The Client Near Cache Statistics tables show statistics related to the Near Cache of a client for maps and caches.

For information about Near Cache, see Best practices in the Platform documentation.

Table 5. Near Cache statistics
Field	Description
Map/Cache Name	Name of the map or cache.
Creation Time	Creation time of this Near Cache on the client.
Evictions	Number of evictions of Near Cache entries owned by the client.
Expirations	Number of TTL and max-idle expirations of Near Cache entries owned by the client.
Hits	Number of hits (reads) of Near Cache entries owned by the client.
Misses	Number of misses of Near Cache entries owned by the client.
Owned Entry Count	Number of Near Cache entries owned by the client.
Owned Entry Memory Cost	Memory cost of Near Cache entries owned by the client.
LP Duration	Duration of the last Near Cache key persistence (when the pre-load feature is enabled).
LP Key Count	Number of Near Cache key persistences (when the pre-load feature is enabled).
LP Time	Time of the last Near Cache key persistence (when the pre-load feature is enabled).
LP Written Bytes	Written number of bytes of the last Near Cache key persistence (when the pre-load feature is enabled).
LP Failure	Failure reason of the last Near Cache persistence (when the pre-load feature is enabled).

See the following topics in the Platform documentation:

Defining Client Labels.