Database managementSystem configuration

System configuration

Enhancing Memgraph’s performance can sometimes involve optimizing operating system-level configurations. These adjustments primarily relate to the settings governing resource allocation and process management.

The following configuration steps are written based on the Ubuntu 22.04 operating system. The steps may vary slightly depending on the Linux distribution you are using.

Handle numerous open files simultaneously

The fs.file-max parameter in Linux sets the maximum number of file handles that the Linux kernel will allocate. This adjustment is important when the system needs to handle numerous open files simultaneously. To adjust this parameter, do the following:

Open `/etc/sysctl.conf` in a text editor

You need root privileges to edit this file, which is used for configuring kernel parameters at runtime.

Set the file handle limit

Add the line fs.file-max=100000 to sysctl.conf.

Apply the changes

Save your changes and exit the text editor. Run sudo sysctl -p to apply the changes immediately without rebooting.

Verify the changes

Run sysctl fs.file-max to check that the new value has been applied. It should return 100000.

Increasing memory map areas

If users are working on a larger scale, there is a possibility that a transaction is hanging because Memgraph tries to allocate memory and it couldn’t as it was out of virtual memory space. User can adjust the vm.max_map_count parameter to define the maximum number of memory map areas a process can have.

Recommended values for the vm.max_map_count parameter

For optimal system performance, the vm.max_map_count value should be chosen in accordance with your system’s RAM, aiming for approximately one memory map area per 128 KB of system memory.

Amount of RAMvm.max_map_count value
8GB - 32GBvm.max_map_count=262144
32GB - 64GBvm.max_map_count=524288
64GB - 128GBvm.max_map_count=1048576
128GB - 256GBvm.max_map_count=2097152
256GB - 512GBvm.max_map_count=4194304
512GB - 1TBvm.max_map_count=8388608
1TB - 1.5TBvm.max_map_count=12582912
1.5TB - 2TBvm.max_map_count=16777216
2TB - 2.5TBvm.max_map_count=20971520
2.5TB - 3TBvm.max_map_count=25165824
3TB - 3.5TBvm.max_map_count=29360128
3.5TB - 4TBvm.max_map_count=33554432

Immediate adjustment

For instance, if your recommended vm.max_map_count value is 262144, run sudo sysctl -w vm.max_map_count=262144 to immediately increase the memory map area limit to 262,144. This change takes effect right away but lasts only until the next reboot.

Persistent adjustment

To ensure that changes to vm.max_map_count persist after a reboot, follow these steps:

Edit `/etc/sysctl.conf`

Add vm.max_map_count=262144 to /etc/sysctl.conf. Root privileges are required for editing.

Apply the changes

Save your changes and run sudo sysctl -p to apply them right away.

Verify the changes

Run sysctl vm.max_map_count to ensure the new value is in effect. It should return 262144.

Addressing stack overflow issues

Stack overflow issues may occur due to a large query in Memgraph. To address these issues, there are two possible approaches:

  1. Increase the stack size
  2. Split the query into smaller chunks

Increase the stack size

With Docker

Run Docker image

Run the Memgraph using:

docker run --rm -it --name memgraph --ulimit stack=33554432:33554432 -p 7687:7687 -p 7444:7444 memgraph/memgraph

Replace 33554432 with the required stack size in bytes.

Verify the changes

To check the new stack size limits, run:

docker exec memgraph sh -c "ulimit -a | grep stack"

This command should return stack(kbytes) 32768, confirming that the new stack size limits have been applied. This value is equivalent of 32MB

Without Docker

Open /etc/security/limits.conf in a text editor

You need root privileges to edit this file. This file is used to set user or group-specific soft and hard limits for various system resources.

Set the stack size limit

Add the following lines to set both the soft and hard stack size limits for the user:

memgraph soft stack 32768
memgraph hard stack 32768

The value 32768 represents the stack size in kilobytes, equivalent to 32MB.

Apply the changes

Save your changes and exit the text editor. For the changes to take effect, the user may need to log out and then log back in.

Verify the changes

To check the new stack size limits, switch to the user account and run:

ulimit -s

This command should return 32768, confirming that the new stack size limits have been applied.

Split the query into smaller chunks

To avoid stack overflow, divide your large query into smaller parts. This approach requires careful handling of variables and node references across queries. For creating edges between nodes created in separate queries, use the MATCH clause to reference nodes from previous queries:

// First Query
CREATE (a:Node {id: 1});
// Second Query
MATCH (a:Node {id: 1})
CREATE (b:Node {id: 2}), (a)-[:RELATES_TO]->(b);

This method reduces the stack size required for each query, potentially avoiding the stack overflow issue.

IPv6 networking configuration

If you are running Memgraph on a system with IPv6 enabled and want to connect via an IPv6 address, you may encounter issues where Memgraph is not reachable over IPv6.

💡

How to check if IPv6 is enabled on your system

Windows

  1. Open Command Prompt (Win + R, type cmd, hit Enter).
  2. Type ipconfig /all.
  3. Look for the “IPv6 Address” section.

Mac/Linux

  1. Open Terminal.
  2. Type ifconfig | grep inet6 or ip -6 addr.
  3. If you see IPv6 addresses, it is enabled.

Here are the possible error messages you might encounter:

Connection failure: couldn't connect to host: Connection refused
Error: Couldn't connect to [::]:7687 (resolved to ('[::]:7687',)):
Failed to read any data from server ResolvedIPv6Address(('::', 7687, 0, 0))

To fix this, disable IPv6 or configure Memgraph to use it.

Configure Memgraph to use IPv6

To configure Memgraph to use IPv6, explicitly instruct the Bolt server to listen on an IPv6 address. To do that, set the --bolt-address configuration to an IPv6 address when starting Memgraph. To start Memgraph with the Bolt server listening on all IPv6 interfaces (::), set --bolt-address=::.

The following command runs Memgraph in Docker with the --bolt-address set to :::

docker run -p 7687:7687 memgraph/memgraph:latest --bolt-address=::

When connecting to the running Memgraph instance with mgconsole or a certain driver, then the host parameter or URI must be set to :: (corresponding to IPv4 0.0.0.0) or ::1 (corresponding to IPv4 127.0.0.1). Network’s IPv6 can be used to connect from a client if everything is running in a explicit IPv6 Docker network.

If you are using monitoring server or metrics, they should be configured to connect to the IPv6 address as well.

SSL encryptionDeployment