To store encrypted git credentials on disk in Ubuntu, install pass and the git-credential-manager. We will use gpg to generate a key that pass will use for secure storage and retrieval of credentials. Use these commands to get everything set up for git:
saint@ubuntuvm:~/repos/scratchpad$ git push
Username for 'https://github.com': swesonga
Password for 'https://swesonga@github.com':
remote: Permission to swesonga/scratchpad.git denied to swesonga.
fatal: unable to access 'https://github.com/swesonga/scratchpad/': The requested URL returned error: 403
saint@ubuntuvm:~/repos/scratchpad$ sudo dpkg -i ~/Downloads/gcm-linux_amd64.2.1.2.deb
[sudo] password for saint:
Selecting previously unselected package gcm.
(Reading database ... 272980 files and directories currently installed.)
Preparing to unpack .../gcm-linux_amd64.2.1.2.deb ...
Unpacking gcm (2.1.2) ...
Setting up gcm (2.1.2) ...
saint@ubuntuvm:~/repos/scratchpad$ which git-credential-manager
/usr/local/bin/git-credential-manager
saint@ubuntuvm:~/repos/scratchpad$ git-credential-manager configure
Configuring component 'Git Credential Manager'...
Configuring component 'Azure Repos provider'...
The git push experience is now different:
saint@ubuntuvm:~/repos/scratchpad$ git push
fatal: No credential store has been selected.
Set the GCM_CREDENTIAL_STORE environment variable or the credential.credentialStore Git configuration setting to one of the following options:
secretservice : freedesktop.org Secret Service (requires graphical interface)
gpg : GNU `pass` compatible credential storage (requires GPG and `pass`)
cache : Git's in-memory credential cache
plaintext : store credentials in plain-text files (UNSECURE)
See https://aka.ms/gcm/credstores for more information.
Username for 'https://github.com':
saint@ubuntuvm:~/repos/scratchpad$ git config --global credential.credentialStore
saint@ubuntuvm:~/repos/scratchpad$ git push
fatal: Password store has not been initialized at '/home/saint/.password-store'; run `pass init <gpg-id>` to initialize the store.
See https://aka.ms/gcm/credstores for more information.
Username for 'https://github.com':
Since I own the VM, I don’t mind credentials being stored on disk (but not in plain text), so I set up gpg and pass as instructed.
saint@ubuntuvm:~$ gpg --gen-key
gpg (GnuPG) 2.2.27; Copyright (C) 2021 Free Software Foundation, Inc.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Note: Use "gpg --full-generate-key" for a full featured key generation dialog.
GnuPG needs to construct a user ID to identify your key.
Real name: Saint Wesonga
Email address: saint@swesonga.org
You selected this USER-ID:
"Saint Wesonga <saint@swesonga.org>"
...
saint@ubuntuvm:~$ sudo apt install pass
[sudo] password for saint:
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
The following additional packages will be installed:
libqrencode4 qrencode tree xclip
Suggested packages:
libxml-simple-perl python ruby
The following NEW packages will be installed:
libqrencode4 pass qrencode tree xclip
0 upgraded, 5 newly installed, 0 to remove and 92 not upgraded.
Need to get 151 kB of archives.
After this operation, 442 kB of additional disk space will be used.
Do you want to continue? [Y/n]
...
saint@ubuntuvm:~$ pass init ABCDEF0123456789
mkdir: created directory '/home/saint/.password-store/'
Password store initialized for ABCDEF0123456789
Apparently I used the wrong value for the key but git push is unfazed – it pushes successfully after the browser authentication completes. I’m not sure what is happening now since browser authentication is in use but as long as I can push, I can forge ahead with other tasks.
saint@ubuntuvm:~/repos/scratchpad$ git push
info: please complete authentication in your browser...
fatal: Failed to encrypt file '/home/saint/.password-store/git/https/github.com/swesonga.gpg' with gpg. exit=2, out=, err=gpg: <WRONG HEX VALUE>: skipped: No public key
gpg: [stdin]: encryption failed: No public key
Enumerating objects: 11, done.
Counting objects: 100% (11/11), done.
Delta compression using up to 6 threads
Compressing objects: 100% (5/5), done.
Writing objects: 100% (6/6), 745 bytes | 745.00 KiB/s, done.
Total 6 (delta 3), reused 0 (delta 0), pack-reused 0
remote: Resolving deltas: 100% (3/3), completed with 3 local objects
Update: 2023-09-20. Use pass rm -r git to authenticate in the browser the next time git push is executed (e.g. if the password store secret is lost).
When Experimenting with perf on Linux, I used an Ubuntu VM. This can be a bit more cumbersome when simply trying to understand what various Linux commands can do. I decided to try using WSL to experiment with perf. Running wsl from the command line was sufficient to determine how to install the Ubuntu distribution.
C:\dev> wsl
Windows Subsystem for Linux has no installed distributions.
Distributions can be installed by visiting the Microsoft Store:
https://aka.ms/wslstore
C:\dev> wsl --install
Windows Subsystem for Linux is already installed.
The following is a list of valid distributions that can be installed.
Install using 'wsl --install -d <Distro>'.
NAME FRIENDLY NAME
Ubuntu Ubuntu
Debian Debian GNU/Linux
kali-linux Kali Linux Rolling
Ubuntu-18.04 Ubuntu 18.04 LTS
Ubuntu-20.04 Ubuntu 20.04 LTS
Ubuntu-22.04 Ubuntu 22.04 LTS
OracleLinux_7_9 Oracle Linux 7.9
OracleLinux_8_7 Oracle Linux 8.7
OracleLinux_9_1 Oracle Linux 9.1
SUSE-Linux-Enterprise-Server-15-SP4 SUSE Linux Enterprise Server 15 SP4
openSUSE-Leap-15.4 openSUSE Leap 15.4
openSUSE-Tumbleweed openSUSE Tumbleweed
C:\dev> wsl --install -d Ubuntu-22.04
Installing: Ubuntu 22.04 LTS
Ubuntu 22.04 LTS has been installed.
Launching Ubuntu 22.04 LTS...
Creating a UNIX user account
Installing perf
Install the linux-tools-generic package then check the perf version as follows:
Once the WSL Ubuntu distro installation completed and I have created a user account, I start by checking the perf --version lets you know how it can be installed:
saint@machine:~$ perf --version
Command 'perf' not found, but can be installed with:
sudo apt install linux-intel-iotg-tools-common # version 5.15.0-1027.32, or
sudo apt install linux-nvidia-tools-common # version 5.15.0-1023.23
sudo apt install linux-tools-common # version 5.15.0-71.78
sudo apt install linux-nvidia-5.19-tools-common # version 5.19.0-1009.9
sudo apt install linux-nvidia-tegra-tools-common # version 5.15.0-1012.12
Since I’m not looking for anything vendor specific, I try to install the linux-tools-common package.
saint@machine:~$ sudo apt install linux-tools-common
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
The following NEW packages will be installed:
linux-tools-common
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 290 kB of archives.
After this operation, 823 kB of additional disk space will be used.
Ign:1 http://archive.ubuntu.com/ubuntu jammy-updates/main amd64 linux-tools-common all 5.15.0-71.78
Err:1 http://security.ubuntu.com/ubuntu jammy-updates/main amd64 linux-tools-common all 5.15.0-71.78
404 Not Found [IP: ... 80]
E: Failed to fetch http://security.ubuntu.com/ubuntu/pool/main/l/linux/linux-tools-common_5.15.0-71.78_all.deb 404 Not Found [IP: ... 80]
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?
saint@machine:~$ sudo apt install linux-tools-common
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
The following NEW packages will be installed:
linux-tools-common
0 upgraded, 1 newly installed, 0 to remove and 41 not upgraded.
Need to get 277 kB of archives.
After this operation, 833 kB of additional disk space will be used.
Get:1 http://archive.ubuntu.com/ubuntu jammy-updates/main amd64 linux-tools-common all 5.15.0-73.80 [277 kB]
Fetched 277 kB in 0s (793 kB/s)
Selecting previously unselected package linux-tools-common.
(Reading database ... 24137 files and directories currently installed.)
Preparing to unpack .../linux-tools-common_5.15.0-73.80_all.deb ...
Unpacking linux-tools-common (5.15.0-73.80) ...
Setting up linux-tools-common (5.15.0-73.80) ...
Processing triggers for man-db (2.10.2-1) ...
Can we run a perf command now? No, perf not found for my kernel.
saint@machine:~$ perf --version
WARNING: perf not found for kernel 5.10.102.1-microsoft
You may need to install the following packages for this specific kernel:
linux-tools-5.10.102.1-microsoft-standard-WSL2
linux-cloud-tools-5.10.102.1-microsoft-standard-WSL2
You may also want to install one of the following packages to keep up to date:
linux-tools-standard-WSL2
linux-cloud-tools-standard-WSL2
Is that really my kernel version? Yes it is.
saint@mymachine:~$ uname -a
Linux mymachine 5.10.102.1-microsoft-standard-WSL2 #1 SMP Wed Mar 2 00:30:59 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux
Unfortunately, the suggested packages cannot be found:
saint@machine:~$ sudo apt install linux-tools-standard-WSL2
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
E: Unable to locate package linux-tools-standard-WSL2
saint@machine:~$ sudo apt install linux-tools-5.10.102.1-microsoft-standard-WSL2
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
E: Unable to locate package linux-tools-5.10.102.1-microsoft-standard-WSL2
E: Couldn't find any package by glob 'linux-tools-5.10.102.1-microsoft-standard-WSL2'
nt@machine:~$ sudo apt-get install linux-tools-5.10.102.1-microsoft-standard-WSL2
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
E: Unable to locate package linux-tools-5.10.102.1-microsoft-standard-WSL2
E: Couldn't find any package by glob 'linux-tools-5.10.102.1-microsoft-standard-WSL2'
E: Couldn't find any package by regex 'linux-tools-5.10.102.1-microsoft-standard-WSL2'
The interesting thing about this is that the version numbers shown in the list of packages to be installed do not match my kernel version. However, the installation succeeds.
saint@machine:~$ sudo apt install linux-tools-generic
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
The following additional packages will be installed:
linux-tools-5.15.0-73 linux-tools-5.15.0-73-generic
The following NEW packages will be installed:
linux-tools-5.15.0-73 linux-tools-5.15.0-73-generic linux-tools-generic
0 upgraded, 3 newly installed, 0 to remove and 41 not upgraded.
Need to get 7931 kB of archives.
After this operation, 27.3 MB of additional disk space will be used.
Do you want to continue? [Y/n] y
Get:1 http://archive.ubuntu.com/ubuntu jammy-updates/main amd64 linux-tools-5.15.0-73 amd64 5.15.0-73.80 [7926 kB]
Get:2 http://archive.ubuntu.com/ubuntu jammy-updates/main amd64 linux-tools-5.15.0-73-generic amd64 5.15.0-73.80 [1786 B]
Get:3 http://archive.ubuntu.com/ubuntu jammy-updates/main amd64 linux-tools-generic amd64 5.15.0.73.71 [2308 B]
Fetched 7931 kB in 2s (5163 kB/s)
Selecting previously unselected package linux-tools-5.15.0-73.
(Reading database ... 24210 files and directories currently installed.)
Preparing to unpack .../linux-tools-5.15.0-73_5.15.0-73.80_amd64.deb ...
Unpacking linux-tools-5.15.0-73 (5.15.0-73.80) ...
Selecting previously unselected package linux-tools-5.15.0-73-generic.
Preparing to unpack .../linux-tools-5.15.0-73-generic_5.15.0-73.80_amd64.deb ...
Unpacking linux-tools-5.15.0-73-generic (5.15.0-73.80) ...
Selecting previously unselected package linux-tools-generic.
Preparing to unpack .../linux-tools-generic_5.15.0.73.71_amd64.deb ...
Unpacking linux-tools-generic (5.15.0.73.71) ...
Setting up linux-tools-5.15.0-73 (5.15.0-73.80) ...
Setting up linux-tools-5.15.0-73-generic (5.15.0-73.80) ...
Setting up linux-tools-generic (5.15.0.73.71) ...
perf --version still fails though. It’s not a symlink to anything else.
saint@machine:~$ ls -l `which perf`
-rwxr-xr-x 1 root root 1622 May 15 07:10 /usr/bin/perf
However, there is a user that was able to use perf by running the tool in the /usr/lib/linux-tools/… directory. Sure enough, this does the trick!
saint@machine:~$ /usr/lib/linux-tools/5.15.0-73-generic/perf --version
perf version 5.15.98
Sharing Files Between Windows and WSL Ubuntu
I was curious about whether I could generate a report from a perf.data file generated on another machine. The docs on Working across file systems show how easy it is to use a file on the Windows file system:
cd /mnt/c/dev/reports
/usr/lib/linux-tools/5.15.0-73-generic/perf report -n --stdio > report.txt
This doesn’t work though. The command fails after about 40 seconds with the error No kallsyms or vmlinux with build-id 5c3d8... was found.
mkdir -p ~/java/binaries/jdk/x64
cd ~/java/binaries/jdk/x64
wget https://aka.ms/download-jdk/microsoft-jdk-17.0.7-linux-x64.tar.gz
tar xzf microsoft-jdk-17.0.7-linux-x64.tar.gz
Test the factorization application to verify that the Java build works.
export JAVA_HOME=~/java/binaries/jdk/x64/jdk-17.0.7+7
cd ~/repos/scratchpad/demos/java/FindPrimes
$JAVA_HOME/bin/javac Factorize.java
$JAVA_HOME/bin/java Factorize 123890571352112309857
# Use 4 threads to speed things up
$JAVA_HOME/bin/java Factorize 123890571352112309857 CUSTOM_THREAD_COUNT_VIA_THREAD_CLASS 4
We will need the PrintAssembly option to disassemble the code generated by the compiler when running a Java program. This option requires diagnostic VM options to be unlocked. This is the full command line for generating the disassembly from the application’s execution. The output is redirected to a code.asm file since it can be voluminous.
In the above example, I have used a Java build in a custom path. If you are using a Java build that is already installed, then a few extra steps might be needed to determine where the JAVA_HOME path, e.g.
saint@ubuntuvm:~$ which java
/usr/bin/java
saint@ubuntuvm:~$ ls -l `which java`
saint@ubuntuvm:~$ ls -l /etc/alternatives/java
In the post on Experimenting with Async Profiler, I mentioned the basic (trial division) integer factorization app I wrote. I’ve been experimenting with perf to see what the system looks like when running this application. On Ubuntu, I started with this command:
perf record -F 97 -a -g -- sleep 10
Turns out perf isn’t installed by default.
WARNING: perf not found for kernel 5.19.0-41
You may need to install the following packages for this specific kernel:
linux-tools-5.19.0-41-generic
linux-cloud-tools-5.19.0-41-generic
You may also want to install one of the following packages to keep up to date:
linux-tools-generic
linux-cloud-tools-generic
Interestingly, running sudo apt install linux-tools-generic only picks up 5.17:
...
The following NEW packages will be installed:
linux-tools-5.15.0-72 linux-tools-5.15.0-72-generic linux-tools-generic
...
which perf now shows /usr/bin/perf but even perf -v fails with the above warning so I have to run
sudo apt install linux-tools-5.19.0-41-generic
...
The following NEW packages will be installed:
linux-hwe-5.19-tools-5.19.0-41 linux-tools-5.19.0-41-generic
...
Once that completes, perf can now run but perf version doesn’t display anything meaningful. Back to the original command:
perf record -F 97 -a -g -- sleep 10
This fails with an error about restricted access. Interesting reading but I just use sudo and carry on.
Error:
Access to performance monitoring and observability operations is limited.
Consider adjusting /proc/sys/kernel/perf_event_paranoid setting to open
access to performance monitoring and observability operations for processes
without CAP_PERFMON, CAP_SYS_PTRACE or CAP_SYS_ADMIN Linux capability.
More information can be found at 'Perf events and tool security' document:
https://www.kernel.org/doc/html/latest/admin-guide/perf-security.html
perf_event_paranoid setting is 4:
-1: Allow use of (almost) all events by all users
Ignore mlock limit after perf_event_mlock_kb without CAP_IPC_LOCK
>= 0: Disallow raw and ftrace function tracepoint access
>= 1: Disallow CPU event access
>= 2: Disallow kernel profiling
To make the adjusted perf_event_paranoid setting permanent preserve it
in /etc/sysctl.conf (e.g. kernel.perf_event_paranoid = <setting>)
Once the command completes, a perf.data file is created in the current directory. To generate a report, run this command. See the sample perf-report.txt file on GitHub.
perf report -n --stdio > perf-report.txt
To generate a flame graph, use Brendan Gregg’s scripts:
cd ~/repos
git clone https://github.com/brendangregg/FlameGraph
cd -
perf script --header > stacks.txt
~/repos/FlameGraph/stackcollapse-perf.pl < stacks.txt | ~/repos/FlameGraph/flamegraph.pl --hash > myflamegraph.svg
I have been studying the performance of a simple Java application (for integer factorization) using async-profiler. The application’s source code is on GitHub.
async-profiler is a low overhead sampling profiler for Java that does not suffer from Safepoint bias problem.
Once the application is running, use the profiler.sh script to attach to the Java process and start profiling it. I was interested in wall clock profiling. This is specified using the -e wall argument (see Part 2: Improving Performance with Async-profiler by Andrei Pangin. – YouTube). The command line below will profile the Java application with a 5ms sampling interval for a duration (-d) of 10 seconds.
# macos:
cd ~/java/binaries/async-profiler-2.9-macos
# Linux:
cd ~/java/binaries/async-profiler-2.9-linux
./profiler.sh -e wall -t -i 5ms -d 10 -f result.html jps
The jps argument above lets the profiler.sh script determine which Java process is running by calling The jps Command (oracle.com). If there are multiple Java processes, then run jps first to determine the process id of the one to be profiled then explicitly pass that pid to profiler.sh e.g.
To find out file types on macos, run file -I rawdata. In my case, I had flamegraph data that was shared as application/gzip (causing unzip to fail with End-of-central-directory signature not found. I needed to use gzip -d rawdata.
We use SymChk to ensure that symbols are available for Windows applications. For the OpenJDK build, this command line can be used to ensure the symbols directory contains symbols for all the Java binaries:
/r causes SymChk to recursively search all subdirectories under the D:\java\binaries\jdk\x64\jdk-17.0.7+7\ directory for program files.
/s specifies the directories containing symbols and multiple directories should be separated with semicolons
Here’s the tail end of the SymChk output:
...
SYMCHK: api-ms-win-crt-utility-l1-1-0.dll FAILED - api-ms-win-crt-utility-l1-1-0.pdb mismatched or not found
SYMCHK: msvcp140.dll FAILED - msvcp140.amd64.pdb mismatched or not found
SYMCHK: ucrtbase.dll FAILED - ucrtbase.pdb mismatched or not found
SYMCHK: vcruntime140.dll FAILED - vcruntime140.amd64.pdb mismatched or not found
SYMCHK: vcruntime140_1.dll FAILED - vcruntime140_1.amd64.pdb mismatched or not found
SYMCHK: FAILED files = 46
SYMCHK: PASSED + IGNORED files = 440
The components that have failures are binaries that are external dependencies of the OpenJDK. Those failures can therefore be safely ignored. An interesting thing to note is that java.dll and java.exe are in the same folder in the OpenJDK installation. Since their symbol files are both called java.pdb, the symbols for java.exe are placed in a subdirectory called exe. This applies to other binaries with similar PDB filename conflicts. See the Symbol Path Syntax section for more details.
The YCSB_COMMAND passed to the Client class is set to -load and -t respectively, for the load and run arguments to the script. The -db argument specified which class to use for the database client. This comes from the second parameter to the script (grep is used to match the script’s 2nd argument with a line in bindings.properties that specifies the corresponding Java class).
Setting up YSCB with a MySQL Database
Database Installation
In addition to the original paper, Planet MySQL also has YCSB results for runs against a MySQL database. The ease of use of a local database prompts me to start out with MySQL as well. Ubuntu docs explain how to Install and configure a MySQL server.
saint@ubuntuvm2:~$ sudo apt install mysql-server
[sudo] password for saint:
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
The following additional packages will be installed:
libaio1 libcgi-fast-perl libcgi-pm-perl libevent-core-2.1-7
libevent-pthreads-2.1-7 libfcgi-bin libfcgi-perl libfcgi0ldbl
libhtml-template-perl libmecab2 libprotobuf-lite23 mecab-ipadic
mecab-ipadic-utf8 mecab-utils mysql-client-8.0 mysql-client-core-8.0
mysql-common mysql-server-8.0 mysql-server-core-8.0
Suggested packages:
libipc-sharedcache-perl mailx tinyca
The following NEW packages will be installed:
libaio1 libcgi-fast-perl libcgi-pm-perl libevent-core-2.1-7
libevent-pthreads-2.1-7 libfcgi-bin libfcgi-perl libfcgi0ldbl
libhtml-template-perl libmecab2 libprotobuf-lite23 mecab-ipadic
mecab-ipadic-utf8 mecab-utils mysql-client-8.0 mysql-client-core-8.0
mysql-common mysql-server mysql-server-8.0 mysql-server-core-8.0
0 upgraded, 20 newly installed, 0 to remove and 2 not upgraded.
Need to get 29.2 MB of archives.
After this operation, 242 MB of additional disk space will be used.
Do you want to continue? [Y/n]
Getting YCSB Sources
Now that MySQL is installed, we need the YCSB sources to run. I started out by cloning the YCSB repo.
mkdir -p ~/java/benchmarks/ycsb
cd ~/java/benchmarks/ycsb
git clone https://github.com/brianfrankcooper/YCSB
cd YCSB
As a Java repo rookie, I simply ran bin/ycsb.sh load basic -P workloads/workloada as mentioned in the readme without realizing that I needed to first build the repo, duh. That failed with this error:
$ export JAVA_HOME=~/java/binaries/jdk/x64/jdk-20+36
$ bin/ycsb.sh load basic -P workloads/workloada
Error: Could not find or load main class site.ycsb.db.JdbcDBCreateTable
Caused by: java.lang.ClassNotFoundException: site.ycsb.db.JdbcDBCreateTable
Use mvn to build the sources:
# Error: Could not find or load main class site.ycsb.db.JdbcDBCreateTable
# https://github.com/brianfrankcooper/YCSB/issues/257#issuecomment-104845560
sudo apt install maven
mvn clean package
I end up with test failures, what do you know?
Getting YCSB Binaries
I decided I might as well just follow the main readme steps and not deal with any build issues.
cd ~/java/benchmarks/ycsb
sudo apt install curl
curl -O --location https://github.com/brianfrankcooper/YCSB/releases/download/0.17.0/ycsb-0.17.0.tar.gz
tar xfvz ycsb-0.17.0.tar.gz
cd ycsb-0.17.0
Launching YCSB
Launch YCSB in the folder from the tar.gz file:
# Notice the version in the path below needs to be updated from what is used at
# https://github.com/brianfrankcooper/YCSB/tree/master/jdbc
#
# The MySQL connectors are at https://dev.mysql.com/downloads/connector/j/?os=26
java -cp jdbc-binding/lib/jdbc-binding-0.17.0.jar:../mysql-connector-j-8.0.32/mysql-connector-j-8.0.32.jar site.ycsb.db.JdbcDBCreateTable -P myjdbc.properties -n ycsbtable
Turns out the driver in the docs is outdated:
Loading class `com.mysql.jdbc.Driver'. This is deprecated. The new driver class is `com.mysql.cj.jdbc.Driver'. The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary.
Error in creating table. java.sql.SQLException: Access denied for user 'admin'@'localhost' (using password: YES)
CREATE DATABASE ycsb;
CREATE USER 'ycsbuser'@'localhost' IDENTIFIED BY 'ProfileIt!';
GRANT ALL PRIVILEGES ON * . * TO 'ycsbuser'@'localhost';
Hard to believe but the JdbcDBCreateTable class fails!
losing database connection.
Error in creating table. java.sql.SQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'PRIMARY KEY, FIELD0 TEXT, FIELD1 TEXT, FIELD2 TEXT, FIELD3 TEXT, FIELD4 TEXT, FI' at line 1
Loading workload...
Starting test.
Error in initializing the JDBS driver: java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
site.ycsb.DBException: java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
at site.ycsb.db.JdbcDBClient.init(JdbcDBClient.java:228)
at site.ycsb.DBWrapper.init(DBWrapper.java:86)
at site.ycsb.ClientThread.run(ClientThread.java:91)
at java.base/java.lang.Thread.run(Thread.java:833)
Caused by: java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:520)
at java.base/java.lang.Class.forName0(Native Method)
at java.base/java.lang.Class.forName(Class.java:375)
at site.ycsb.db.JdbcDBClient.init(JdbcDBClient.java:199)
... 3 more
bin/ycsb.sh run jdbc -P ../../mysqlworkload.properties
One question that arises is how to control the benchmark running time. There is a maxexecutiontime (in seconds) argument that can be passed to the benchmark.
bin/ycsb.sh run jdbc -P ../../mysqlworkload.properties -p maxexecutiontime=60
The run time is still about 12 seconds and an interesting message is displayed:
Loading workload...
Starting test.
Maximum execution time specified as: 60 secs
Adding shard node URL: jdbc:mysql://127.0.0.1:3306/ycsb
Using shards: 1, batchSize:-1, fetchSize: -1
DBWrapper: report latency for each error is false and specific error codes to track for latency are: []
Could not wait until max specified time, TerminatorThread interrupted.
[OVERALL], RunTime(ms), 6756
Looks like customizing the load is the way to prolong the benchmark:
# The number of records to load into the database initially.
recordcount=1000000
# The target number of operations to perform.
operationcount=10000
# Indicates how many inserts to do if less than recordcount.
# Useful for partitioning the load among multiple servers if the client is the bottleneck.
# Additionally workloads should support the "insertstart" property which tells them which record to start at.
insertcount=10000
If curl fails with error 23 in Cygwin, it is likely that the curl command shipped with Windows is running in the Cygwin terminal instead of the curl binary distributed with Cygwin. To install the Cywin curl command, run the setup executable with these flags:
setup-x86_64.exe -q -P curl
Background
One of the issues I looked into this week was running an AQAvit™ Verification test on Windows and therefore in Cygwin. Here are the environment variables I set and the commands I executed as outlined on the AQAvit™ Verification page.
The last command above (compilation) failed on my Surface Pro X with this error:
...
Buildfile: C:\java\aqa\aqa-tests\TKG\scripts\build_tools.xml
build:
clean:
[delete] Deleting directory C:\java\aqa\aqa-tests\TKG\bin
init:
[mkdir] Created dir: C:\java\aqa\aqa-tests\TKG\bin
getDependentLibs:
[exec] --------------------------------------------
[exec] path is set to /cygdrive/c/java/aqa/aqa-tests/TKG/../TKG/lib
[exec] task is set to default
[exec] dependencyList is set to json_simple
[exec] --------------------------------------------
[exec] Starting download third party dependent jars
[exec] --------------------------------------------
[exec] downloading dependent third party jars to /cygdrive/c/java/aqa/aqa-tests/TKG/../TKG/lib
[exec] downloading https://repo1.maven.org/maven2/com/googlecode/json-simple/json-simple/1.1.1/json-simple-1.1.1.jar
[exec] % Total % Received % Xferd Average Speed Time Time Time Current
[exec] Dload Upload Total Spent Left Speed
[exec]
[exec] 0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0Warning: Failed to open the file Warning: /cygdrive/c/java/aqa/aqa-tests/TKG/../TKG/lib/json-simple.jar: No
[exec] Warning: such file or directory
[exec]
[exec] 5 23931 5 1371 0 0 4483 0 0:00:05 --:--:-- 0:00:05 4509curl: (23) Failure writing output to destination
[exec] ERROR: downloading https://repo1.maven.org/maven2/com/googlecode/json-simple/json-simple/1.1.1/json-simple-1.1.1.jar failed, return code: 5888
BUILD FAILED
C:\java\aqa\aqa-tests\TKG\scripts\build_tools.xml:58: The following error occurred while executing this line:
C:\java\aqa\aqa-tests\TKG\scripts\getDependencies.xml:27: exec returned: 2
I had core.autocrlf set to true when I initially checked out the aqa-tests repo so I suspected the culprit to be a file that didn’t get converted to LF when I ran git add --renormalize as suggested by How do I re-checkout all files in Git to convert from CRLF to LF? – Stack Overflow. I would get errors like “/cygdrive/c/java/aqa/aqa-tests/TKG/scripts/getTestenvProperties.sh: line 14: $’\r’: command not found” and ended up manually changing the line endings using VS Code since there were only 3 files that needed to be changed but I digress…
$ curl -k -o /c/java/aqa/aqa-tests/TKG/lib/file.jar https://repo1.maven.org/maven2/com/googlecode/json-simple/json-simple/1.1.1/json-simple-1.1.1.jar
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0Warning: Failed to open the file /c/java/aqa/aqa-tests/TKG/lib/file.jar: No
Warning: such file or directory
5 23931 5 1371 0 0 4660 0 0:00:05 --:--:-- 0:00:05 4679
curl: (23) Failure writing output to destination
$ curl -k -o ../file.jar https://repo1.maven.org/maven2/com/googlecode/json-simple/json-simple/1.1.1/json-simple-1.1.1.jar
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 23931 100 23931 0 0 84394 0 --:--:-- --:--:-- --:--:-- 84861
Which curl is running? Turns out it’s the native Windows curl command!
I realize there must be a native Cygwin curl package so I install it using this command: \software\setup-x86_64.exe -q -P curl
Installing curl
I end up needing to open a new shell to get it to be picked up when building. That fixes the problem (this version successfully writes the downloaded file to disk)! Here’s the version information for the curl utility installed by Cygwin:
One of my colleagues shared this simple Java program with me.
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.channels.FileChannel;
public class TruncateFile {
public static void main(String[] args) throws IOException {
RandomAccessFile file = new RandomAccessFile("data.txt", "rw");
FileChannel channel = file.getChannel();
channel.map(FileChannel.MapMode.READ_WRITE, 0, 10);
channel.truncate(9);
}
}
This program can be launched using source-file mode for convenience: /c/java/binaries/jdk/x64/jdk-19.0.1+10/bin/java.exe TruncateFile.java. It failed with the exception below:
Exception in thread "main" java.io.IOException: The requested operation cannot be performed on a file with a user-mapped section open
at java.base/sun.nio.ch.FileDispatcherImpl.truncate0(Native Method)
at java.base/sun.nio.ch.FileDispatcherImpl.truncate(FileDispatcherImpl.java:90)
at java.base/sun.nio.ch.FileChannelImpl.truncate(FileChannelImpl.java:490)
at TruncateFile.main(TruncateFile.java:10)
Why does it fail on Windows? I launched Process Monitor, started capturing events, and then ran the above java.exe command and finally stopped capturing events. The SetFileInformationByHandle function failed as indicated by the USER MAPPED FILE entry in its result column.
Process Monitor File Truncation Events
I created a Windows console application, TruncateFile, to also map a file and truncate it using the SetFileInformationByHandle function and therefore get some insight into whether this behavior is the result of a Java bug. Mapping the file using the CreateFileMappingW function indeed fails with ERROR_USER_MAPPED_FILE (The requested operation cannot be performed on a file with a user-mapped section open). This does appear to be a Windows limitation. It is likely the issue another user ran into at Memory mapped file truncation on windows – Stack Overflow.
