tcmalloc | This repository contains the TCMalloc C++ code
kandi X-RAY | tcmalloc Summary
kandi X-RAY | tcmalloc Summary
This repository contains the TCMalloc C++ code. TCMalloc is Google's customized implementation of C's malloc() and C++'s operator new used for memory allocation within our C and C++ code. TCMalloc is a fast, multi-threaded malloc implementation.
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QUESTION
I have a process that consumes a lot of memory on startup, but frees most of that memory after the process is bootstrapped. I see the following in the TCMalloc stats printed afterwards:
...ANSWER
Answered 2021-Jun-08 at 20:18What does this value represent?
It represents the amount of memory that TCMalloc has told the system that it does not need and that the system may use for other purposes.
Has my memory been freed or not?
No. The OS has decided that making it free just to have to make it used again when the program needs it is a waste of effort and has decided instead to switch it directly from one use to another use in a single step rather than going through twice the effort of making it free just to have to make it un-free to use it.
What can I do to prevent this consumption from growing?
Why would you want to? It just makes it easier if the program needs the memory later, minimizes contention on the system's free list, and has no harmful effects at all. TCMalloc has told the OS (via madvise(DONTNEED)
) that the OS may recover the memory and the OS has made the decision that it's not a good idea to make it free just to have to make it used again when it's needed. Do you have some good reason to think the OS is wrong?
It's much easier to just directly transition memory from one us to another in a single step than go through the two steps of making it free just to have to make it used again. The free list can get contended under load and it's much simpler not to use it.
You can force the OS to free it by running some program that consumes a lot of memory and then terminates. That will force the OS to transition the memory to that process and then free it when that process terminates. But this would provide no benefit at all and would be a lot of effort just to eventually increase contention in the memory manager. There is no issue here.
QUESTION
I used to have mongodb (the unofficial package) installed on Ubuntu 20.04. I decided to change to the official one.(version 4.4) First, both packages got confilcted, but after wiping the old one, the install succeeded.
But, when I try to run the mongod service,it fails, and shows this:
...ANSWER
Answered 2021-Jun-04 at 06:00I've found a related question where the same author found the solution, please click here to see:
As a side note, if you have the same error, and provided solutions does not work, please, follow the link and try this answer,but paying special attention to remove both lib and log files created by mongodb,
QUESTION
We chose to deploy the mongos router in the same VM as our applications, but we're running into some issues where the application gets OOM Killed because the mongos eats up a lot more RAM than we'd expect / want to.
After a reboot, the mongos footprint is a bit under 2GB, but from here it constantly requires more memory. About 500MB per week. It went up to 4.5+GB
This is the stats for one of our mongos for the past 2 weeks and it clearly looks like it's leaking memory...
So my question is: how to investigate such behavior? We've not really been able to find explanations as of why the router might require more RAM, or how to diagnosis the behavior much. Or even how to set a memory usage limit to the mongos.
With a db.serverStatus
on the mongos we can see the allocations:
ANSWER
Answered 2021-May-03 at 04:04Why the router would require more memory?
If there is any query in the sharded cluster where the system needs to do a scatter gather then merging activity is taken care of by the mongos itself.
For example I am running a query db.collectionanme.find({something : 1})
If this something field here is not the shard key itself then by default it will do a scatter gather, use explainPlan to check the query. It does a scatter gather because mongos interacts with config server and realises that it doesn't have information for this respective field. {This is applicable for a collection which is sharded}
To make things worse, if you have sorting operations where the index cannot be used then even that now has to be done on the mongos itself. Sorting operations have to block the memory segment to get the pages together based on volume of data then sort works, imagine the best possible Big O for a sorting operation here. Till that is done the memory is blocked for that operation.
What you should do?
Based on settings (your slowms setting, default should be 100ms), check the logs, take a look at your slow queries in the system. If you see a lot of SHARD_MERGE & in memory sorts taking place then you have your culprit right there.
And for quick fix increase the Swap memory availability and make sure settings are apt.
All the best.
QUESTION
I followed mongodb official installation guide to the letter from here Things I tried till now
- removing and reinstalling mongodb
- trying to use mongodb ubuntu package (mongod server wont start in that too with output mongod.service does not exist)
here is the output I am getting
...ANSWER
Answered 2021-Apr-13 at 08:10The s
field in each log object is the severity of the message: I = informational, W = warning, E = Error.
If you look for the first error in that log, you will see it is:
QUESTION
I am trying to set up a MongoDB Docker container to use as a local database for testing, but I am facing issues.
For running the container, I used following command:
docker run -d --name mongodb -p 27017:27017 -e MONGO_INITDB_ROOT_USERNAME="root" -e MONGO_INITDB_ROOT_PASSWORD="password" -v C:\projects\docker\volumes\mongotmp:/data/db mongo:4.4.4
I used -e
to pass the root username and password environment variables, but I am not able to connect to the database, I tried using this connection string:
mongodb://root:password@localhost:27017/?authSource=admin
When I execute a shell inside the container, and try to get the users with db.getUsers()
I get an authentication error.
ANSWER
Answered 2021-Apr-01 at 21:32In MongoDB, users are stored in databases but a database (or databases) that a user has access to doesn't need to be the same as the database in which that user is stored.
The database in which the user is stored is called the authentication database. This is configured via the authSource
URI option and various language-specific driver options, as well as the --authenticationDatabase
mongo shell option.
The error message says that you are authenticating against the test
database. Your earlier shell command shows an attempt to authenticate against the admin
database.
Review which database the user was created in and ensure that you use the same database during authentication.
QUESTION
I was trying to apply a deep learning algorithm(CNN) in python but after separating training-testing data and transforming time series to image step my Colab Notebook crashed and restarted itself again.
It gives an error like "Your session crashed after using all RAM" and when I checked app.log
I saw something about tcmalloc: large alloc. I didn't find anything to fix this crashed.
Do you have any idea how to prevent this warning and fixed this situation?
...ANSWER
Answered 2021-Mar-24 at 20:50Your session ran out of all available RAM. You can purchase Colab Pro
to get extra RAM or you can use a Higher RAM machine and use the Neural Network there
QUESTION
I'm tring to create a text index for multiple fields in a mongodb collection called test but when i run this script in DataGrip
...ANSWER
Answered 2021-Feb-03 at 10:35Probably the problem is a bug in DataGrip or its driver.
SOLUTION: Using Compass or MongoDB Shell it works
QUESTION
ANSWER
Answered 2021-Jan-09 at 19:39Alpine uses musl for its C library. You can either use a different non-alpine based image such as node:12-buster-slim
or any of the other non-Alpine tags here, or try to get it to work by setting up glibc with the instructions here. Using a Debian or Ubuntu based image would be the easiest way forward.
QUESTION
I am using tmux
as my default terminal.
The following is the terminal log, on entering the command sudo mongod
ANSWER
Answered 2021-Jan-28 at 13:51This log output is called "structured log output" and is the only log format of MongoDB as of 4.4. Previous versions used the human-readable log format.
There are tools under development to make this log output human-readable:
- https://github.com/markbenvenuto/mrlog
- Another one that I can't recall at the moment
QUESTION
Mongo version: mongo:4.2.6
I'm following manual Convert a Standalone to a Replica Set to run MongoDB in Replica Set Mode.
When I trying launch MongoDB with command mongod --replSet rs0
- I got the next log: ***aborting after fassert() failure
ANSWER
Answered 2020-Nov-29 at 16:58Seems to me that you performed unclean shutdown of mongod, possibly after it was already running as a RS node, and you got a rollback. At this point the database refuses to start as an RS node since any data rolled back will be lost.
Since you don't have any nodes to resync from, I suggest restoring the standalone data directory that you started with out of a backup (you've taken one, right?) and proceeding with the conversion once again, this time taking care to gracefully shut down mongod until you have an operational replica set with multiple nodes.
Alternatively you can try launching a standalone mongod from this data directory, using mongodump to get a complete data dump, create a new standalone deployment, mongorestore the data into it, then repeat the conversion process to RS node.
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